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Find sin 2a and cot 2a:

 

 Jul 16, 2020
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If cos(a) = 12/13, then the adjacent side is 12 and the hypotenuse is 13 (or a multiple of these).

If the adjacent side is 12 and the hypotenuse is 13, the opposite side is 5 (Pythagorean Theorem).

However, since the angle is in the 4th quadrant, we'll have to make the opposite side = -5.

 

sin(2a)  =  2·sin(a)·cos(a)  =  2·(-5/13)·(12/13)  =  .......

 

cot(2a)  =  1 / tan(2a)  =  1 / (-5/12)  =  ........

 Jul 17, 2020

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