If sin x = 12/37, we have to find cos x. The identity: sin² x + cos² x = 1 ( 12/37)² + cos² x = 1 144 / 1369 + cos² x = 1 cos² x = 1 - 144/1369 cos² x = 1369/1369 - 144/1369 cos² x = 1225 / 1369 cos x = +/- √ 1225/1369 = +/- 35/37 Answer: A ) cos ? = +/- 35 over 37
SOH CAH TOA Lets us know that the Sin of ? Is 12/37; meaning the opposite side is 12, and the hypotenuse is 37. Using the Pythagorean Theorem, we know that 37^2-12^2=B^2 (B being the adjacent side). Once solved, we learn B is 35. Going back to SOH CAH TOA, we know that Cos ?= 35/37; the first option.