(com(AL En(A)) (cos(A-B). m(4-B)) (1, 0) (com(-8), sin(-B) Step 1 dl = d2 Step 2 (cos (A +B)-1)' + sin' (A+ B) = \\(cos A-cos B)' +(sin A + sin B)" Step 3 (cos (1 +B)-1)' +sin'(A+B)=(cos A-cos B)' +(sin A + sin B)' Step 4 cos' (A+ B)-2cos(A+ B)+1+sin'(A+ B)= cos' A-2cos Acos B+ cos' B+ sin' A+2sin Asin B + sin' B Step 5 2-2cos(A+ B)= 2-2cos Acos B +2sin Asin B 1) Doug is trying to prove the sum formula for cosine. He has the diagram shown and starts his proof as shown. What would the next line of the proof be? A) 1 = -sinAsinB B) cos(A + B) = COSACosB + sinAsinB C) cos(A + B) = COSACosB - sinAsinB D) -2cos(A + B) = -2cosAcosB + 2sinAsinB USATestprep, LLC 2021, All Rights Reserved. Read Our BI