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Basic Trigonometry

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Original post by raheem94
See the diagram below:



Use sin in the blue triangle and you are done.

Spoiler



brilliant! one question and sorry if it is a bit of a stupid one but the line r that you drew from the side AO to the middle you labelled it a right angle, how comes wouldn't the right angle be on the other side ?
(edited 11 years ago)
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raheem94
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Original post by Roshniroxy
brilliant! one question and sorry if it is a bit of a stupid one but the line r that you drew from the side AO to the middle you labelled it a right angle, how comes wouldn't the right angle be on the other side ?


It is a right angled triangle because it is a tangent to the circle.

I don't understand what you mean by 'other side'?
Original post by raheem94
It is a right angled triangle because it is a tangent to the circle.

I don't understand what you mean by 'other side'?


:colondollar:
Untitled.png3.1KB
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raheem94
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Original post by Roshniroxy
:colondollar:


No, this angle won't be a right angle.

Remember tangents make an angle of 90degree with the radius of the circle, hence the other angle was a right angle.

So we know one angle is 90 degree and one is 30 degree, so this angle will be 180-(90+30)=180-120=60deg.
Original post by raheem94
No, this angle won't be a right angle.

Remember tangents make an angle of 90degree with the radius of the circle, hence the other angle was a right angle.

So we know one angle is 90 degree and one is 30 degree, so this angle will be 180-(90+30)=180-120=60deg.


Thank you for this ! :smile:

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