SOLUTION: find the exact value of cos 2A and sin 2A given sin A = 12/13, A is in quadrant I

SOLUTION: find the exact value of cos 2A and sin 2A given sin A = 12/13, A is in quadrant I

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Question 752005: find the exact value of cos 2A and sin 2A given sin A = 12/13, A is in quadrant I
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
find the exact value of cos 2A and sin 2A given sin A = 12/13, A is in quadrant I

( working with 5-12-13 right triangle)

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Check with calculator:
sin(A)=12/13 (in Q1)
A=67.38�
2A=134.76
sin(2A)=sin(134.76�)≈0.71
exact value=120/169≈0.71
cos(2A)=cos(134.76�)≈-0.704
exact value=119/169≈-0.704
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