Next 21 pretest: right triangles and trigonometry select the correct answer from each drop-down menu. given: aabc with altitude h two right triangles are formed: one with side lengths c+r, h, and b, and one with side lengths r, h, and a. c br carson starts the proof of the law of cosines with sin (a) = by the definition of the sine ratio and cos (a) = cosine ratio. what are the next steps in the proof? use the then, carson can write an expression for side next, he can use the to rewrite each trigonometric equation in terms of the numerator. in terms of to relate a, b, c, and a