Kakakaty
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The graph is below but my answer is

Yes, Lines A and B are perpendicular this is because they both intercept causing a right angle and they are opposite reciprocals of each other
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Kakakaty
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medicalsupernova
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Did you calculate the gradient of each line?
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davros
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(Original post by Kakakaty)
The graph is below but my answer is

Yes, Lines A and B are perpendicular this is because they both intercept causing a right angle and they are opposite reciprocals of each other
I haven't checked, but if you are sure that the lines are perpendicular then you need to say something about their gradients.
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Kakakaty
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(Original post by medicalsupernova)
Did you calculate the gradient of each line?
Oh no I didnt, I just did and I get different answers does that mean they're not?
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Kakakaty
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Anyone know?
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davros
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(Original post by Kakakaty)
Oh no I didnt, I just did and I get different answers does that mean they're not?
What are your values for the gradients of each line?

What do you know about the gradients of perpendicular lines?
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Kakakaty
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(Original post by davros)
What are your values for the gradients of each line?

What do you know about the gradients of perpendicular lines?
for A i got 3 and for B i got 2.5
I know that their gradients will multiply together to give -1 but from the gradient I got they don't equal -1 so does that mean theyre not perpendicular or did i do my calculations wrong?
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mnot
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(Original post by Kakakaty)
Oh no I didnt, I just did and I get different answers does that mean they're not?
their gradients need to be negative recipricles of each other to be perpendicular.
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davros
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(Original post by mnot)
their gradients need to be negative recipricles of each other to be perpendicular.
I think you mean reciprocals for anyone trying to google this
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Melvin Guna
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(Original post by Kakakaty)
Anyone know?
hint: the Tan theta1 and Tan theta 2 has a relationship for perpendicular lines
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Kakakaty
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(Original post by Melvin Guna)
hint: the Tan theta1 and Tan theta 2 has a relationship for perpendicular lines
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I'm not too sure what this means, could you explain some more?
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Melvin Guna
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(Original post by Kakakaty)
I'm not too sure what this means, could you explain some more?
So the slope of one line is Tan theta 1 and the other is Tan theta 2. The product of the values of these slopes has to equal -1 for the lines to be perpendicular. You can calculate both Tan theta values by counting the boxes since they are the same size
Last edited by Melvin Guna; 3 days ago
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mqb2766
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(Original post by Kakakaty)
for A i got 3 and for B i got 2.5
I know that their gradients will multiply together to give -1 but from the gradient I got they don't equal -1 so does that mean theyre not perpendicular or did i do my calculations wrong?
You must realise line B has a negative gradient as it goes down.
Also the gradient of line A is < 1.
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Kakakaty
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(Original post by mqb2766)
You must realise line B has a negative gradient as it goes down.
Also the gradient of line A is < 1.
I'm not sure what else to do, I keep getting the same answer of A = 3 and for B = 2.5
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Always_Confused
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Hello! For each line, work out the equation of the line in the form y = mx + c, where m is your gradient, c is your y intercept.
For A: You can see in the graph your y intercept is 4. Pick a point on the line that is clear i.e (6,6) and sub these numbers in for y and x. Rearrange to calculate m(a).
For B: Your Y intercept is 10. Do the same for a point that lies on B. (2,5) for example. Rearrange to calculate m(b)

Does m(a) x m(b) = -1?
If yes, they are perpendicular
If no, they're not
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Melvin Guna
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(Original post by Always_Confused)
Hello! For each line, work out the equation of the line in the form y = mx + c, where m is your gradient, c is your y intercept.
For A: You can see in the graph your y intercept is 4. Pick a point on the line that is clear i.e (6,6) and sub these numbers in for y and x. Rearrange to calculate m(a).
For B: Your Y intercept is 10. Do the same for a point that lies on B. (2,5) for example. Rearrange to calculate m(b)

Does m(a) x m(b) = -1?
If yes, they are perpendicular
If no, they're not
This tricks works well too
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mqb2766
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A quick Google
https://www.mathsisfun.com/gradient.html
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Melvin Guna
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Good one, especially this part
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mqb2766
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(Original post by Melvin Guna)
Good one, especially this part
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Not sure what you mean?
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