You are given that sin(A) = -7/25, with A in Quadrant 4, and sin(B) = -12/13, with B in Quadrant 3. Find cos(A+B). Give your answer as a fraction.
Added by Yvonne N.
Step 1
Since A is in Quadrant 4, cos(A) is positive. We can use the Pythagorean identity sin^2(A) + cos^2(A) = 1 to find cos(A). So, cos^2(A) = 1 - sin^2(A) = 1 - (-7/25)^2 = 1 - 49/625 = 576/625. Show more…
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