# Isaac Physics Question

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https://isaacphysics.org/questions/f...9_20_week06See it here. I'm stuck, as I'm not entirely sure what angle I am supposed to find in order to find the relationship between the similar triangles

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#3

(Original post by

https://isaacphysics.org/questions/f...9_20_week06See it here. I'm stuck, as I'm not entirely sure what angle I am supposed to find in order to find the relationship between the similar triangles

**michaelathome**)https://isaacphysics.org/questions/f...9_20_week06See it here. I'm stuck, as I'm not entirely sure what angle I am supposed to find in order to find the relationship between the similar triangles

(Original post by

bump

**michaelathome**)bump

The best way is always to describe your confusion in detail and tell us what have you gotten in attempting the problem.

You can work out to find the angle θ

_{3}, as shown in the picture. The diagram is NOT DRAWN TO SCALE.

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(Original post by

By bumping your own thread would not help in most of the circumstances especially it is within the same day.

The best way is always to describe your confusion in detail and tell us what have you gotten in attempting the problem.

You can work out to find the angle θ

**Eimmanuel**)By bumping your own thread would not help in most of the circumstances especially it is within the same day.

The best way is always to describe your confusion in detail and tell us what have you gotten in attempting the problem.

You can work out to find the angle θ

_{3}, as shown in the picture. The diagram is NOT DRAWN TO SCALE.
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#5

(Original post by

Thanks for the reply. I have gotten the angle to be 30.34 degrees. Then I have resolved a triangle taking the height as 2.5cm to give the length of 1.463cm. Adding this onto 2.5cm from the 45 degree triangle in the bottom right corner has given d equal to 3.963. I'm not sure if my process is correct though. Thanks

**michaelathome**)Thanks for the reply. I have gotten the angle to be 30.34 degrees. Then I have resolved a triangle taking the height as 2.5cm to give the length of 1.463cm. Adding this onto 2.5cm from the 45 degree triangle in the bottom right corner has given d equal to 3.963. I'm not sure if my process is correct though. Thanks

For θ

_{3}to be 30.54 deg,

*d*cannot be 3.963 cm (if I did not misunderstand what you described) as this does not make sense.

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(Original post by

I cannot really understand your "working". It would be better that you make labels to your calculations.

For θ

**Eimmanuel**)I cannot really understand your "working". It would be better that you make labels to your calculations.

For θ

_{3}to be 30.54 deg,*d*cannot be 3.963 cm (if I did not misunderstand what you described) as this does not make sense.If θ3 equals 30.54, and h equals 2.5cm, then we can separate one triangle into two triangles and add the bases. 2.5Tan(30.34) + 2.5tan(45) gives us 3.963cm...

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#7

(Original post by

https://imgur.com/9xLDoK3 See this

If θ3 equals 30.54, and h equals 2.5cm, then we can separate one triangle into two triangles and add the bases. 2.5Tan(30.34) + 2.5tan(45) gives us 3.963cm...

**michaelathome**)https://imgur.com/9xLDoK3 See this

If θ3 equals 30.54, and h equals 2.5cm, then we can separate one triangle into two triangles and add the bases. 2.5Tan(30.34) + 2.5tan(45) gives us 3.963cm...

*θ*

_{3}in here is different from what I implied in my drawing in post #3.

In my drawing in post #3,

*θ*

_{3}is the angle between light ray (black line) and normal (light blue line) and you change the meaning of

*θ*

_{3}in your own drawing in post #6.

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(Original post by

Your

In my drawing in post #3,

**Eimmanuel**)Your

*θ*_{3}in here is different from what I implied in my drawing in post #3.In my drawing in post #3,

*θ*_{3}is the angle between light ray (black line) and normal (light blue line) and you change the meaning of*θ*_{3}in your own drawing in post #6.
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#9

(Original post by

Right. How can I get the base from theta 3 considering that it doesn't form a right angled triangle?

**michaelathome**)Right. How can I get the base from theta 3 considering that it doesn't form a right angled triangle?

You can see there is a right-angled triangle as shown by the dotted yellow lines in the diagram below which involves

*θ*

_{3}.

I highly recommend that you re-draw your own diagram to understand the various angles and the given info.

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(Original post by

Not really sure I understand your question.

You can see there is a right-angled triangle as shown by the dotted yellow lines in the diagram below which involves

I highly recommend that you re-draw your own diagram to understand the various angles and the given info.

**Eimmanuel**)Not really sure I understand your question.

You can see there is a right-angled triangle as shown by the dotted yellow lines in the diagram below which involves

*θ*_{3}.I highly recommend that you re-draw your own diagram to understand the various angles and the given info.

Considering that right angled triangle you drew, and the sketch I have made of it, I am trying to find angle X to get the base of the triangle. Angle X consists of theta 3 + another angle (let this be alpha), (the one between theta 3 and h in your diagram). How do I find alpha, considering I have no other information.

Theta 3 on its own does not make a right angled triangle, it makes a triangle that looks like this https://imgur.com/z1GWwfC. The red is the right angled triangle you drew

Last edited by michaelathome; 6 months ago

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#11

(Original post by

https://imgur.com/R6rXWGi

Considering that right angled triangle you drew, and the sketch I have made of it, I am trying to find angle X to get the base of the triangle. Angle X consists of theta 3 + another angle (let this be alpha), (the one between theta 3 and h in your diagram). How do I find alpha, considering I have no other information.

Theta 3 on its own does not make a right angled triangle, it makes a triangle that looks like this https://imgur.com/z1GWwfC. The red is the right angled triangle you drew

**michaelathome**)https://imgur.com/R6rXWGi

Considering that right angled triangle you drew, and the sketch I have made of it, I am trying to find angle X to get the base of the triangle. Angle X consists of theta 3 + another angle (let this be alpha), (the one between theta 3 and h in your diagram). How do I find alpha, considering I have no other information.

Theta 3 on its own does not make a right angled triangle, it makes a triangle that looks like this https://imgur.com/z1GWwfC. The red is the right angled triangle you drew

You really need to relook on the diagram that I had drawn.

The yellow dotted line triangle

**DOES NOT**correspond to the partial red triangle you had drawn.

This is why I mention you should redraw the diagram on your own (using paper, pencil and ruler) to better understand the angles instead of just “blindly” applying my diagram. My diagram makes sense to me but it may not make sense to you if you don’t really understand what I am drawing.

Don’t be too quick to reply. All the info is really in the diagram if you really draw on your own and fill in your own labels which I did not label. Do not rely on other people diagram to solve the problem. Draw your own to make sense or else you are blindly searching for an answer.

Below is the diagram that I have shown in post #9.

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(Original post by

You really need to relook on the diagram that I had drawn.

The yellow dotted line triangle

This is why I mention you should redraw the diagram on your own (using paper, pencil and ruler) to better understand the angles instead of just “blindly” applying my diagram. My diagram makes sense to me but it may not make sense to you if you don’t really understand what I am drawing.

Don’t be too quick to reply. All the info is really in the diagram if you really draw on your own and fill in your own labels which I did not label. Do not rely on other people diagram to solve the problem. Draw your own to make sense or else you are blindly searching for an answer.

Below is the diagram that I have shown in post #9.

**Eimmanuel**)You really need to relook on the diagram that I had drawn.

The yellow dotted line triangle

**DOES NOT**correspond to the partial red triangle you had drawn.This is why I mention you should redraw the diagram on your own (using paper, pencil and ruler) to better understand the angles instead of just “blindly” applying my diagram. My diagram makes sense to me but it may not make sense to you if you don’t really understand what I am drawing.

Don’t be too quick to reply. All the info is really in the diagram if you really draw on your own and fill in your own labels which I did not label. Do not rely on other people diagram to solve the problem. Draw your own to make sense or else you are blindly searching for an answer.

Below is the diagram that I have shown in post #9.

I have drawn out your diagram, and understand why it is 'this way'. I just do not understand how I am supposed to find the base with only one angle and one side that is not directly linked to the same triangle. I have tried to use the Z-rule but I confident that this incorrect. It would be more helpful if you simply walked me through your basic process rather than reiterating the same points. I will not be able to acknowledge my mistakes made in this question by never knowing them.

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