If-cos-1-x-a-cos-1-y-b-prove-x-2-a-2-2xy-ab-cos-y-2-b-2-sin-2- Tinku Tara June 3, 2023 Trigonometry 0 Comments FacebookTweetPin Question Number 10948 by rish@bh last updated on 03/Mar/17 Ifcos−1xa+cos−1yb=αprovex2a2−2xyabcosα+y2b2=sin2α Answered by ajfour last updated on 03/Mar/17 letθ+∅=αcos(θ+∅)=cosαcosθcos∅−sinθsin∅=cosα(xa)(yb)−a2−x2a.b2−y2b=cosα(xyab−cosα)2=(1−x2a2)(1−y2b2)−2xycosαab+cos2α=1−x2a2−y2b2x2a2−2xycosαab+y2b2=sin2α. Commented by rish@bh last updated on 03/Mar/17 Thankyou Terms of Service Privacy Policy Contact: info@tinkutara.com FacebookTweetPin Post navigation Previous Previous post: In-a-triangle-ABC-prove-the-following-a-b-c-2-a-2-b-2-c-2-cot-A-2-cot-B-2-cot-C-2-cot-A-cot-B-cot-C-Next Next post: S-n-k-0-n-1-n-k-n-k- Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Comment * Name * Save my name, email, and website in this browser for the next time I comment.