A. if cosθ=−45 where θ is in quadrant 3, find sin2θ. b. if cosθ=2√2 where θ is in quadrant 1, find cos2θ. c. if sinθ=817 where θ is in quadrant 2, find tan2θ.

Part A)

Part B)

Part C)

Step-by-step explanation:

Part A) we have

θ is in quadrant 3 ----> the sine is negative

Find

we know that

Remember that

substitute

---> remember that the sine is negative (3 quadrant)

Find

we have

substitute

Part B) we have

θ is in quadrant 1

Find      

we know that

substitute

Part C) we have

θ is in quadrant 2 ----> the cosine is negative

Find  

we know that

Remember that

substitute

Find  

substitute

Find  

substitute

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12