Prove thatCos²A+cost(A+B)-2cosA.cosB.cos(A+B)=sin²B
Prove that
Cos²A+cost(A+B)-2cosA.cosB.cos(A+B)=sin²B
Monal pawar , 7 Years ago
Grade 11
Trigonometry> Prove that Cos²A+cost(A+B)-2cosA.cosB.cos...
1 Answers
Arun
Dear student
Cos²A + cos(A+B) [cosA cosB - sinA sinB- 2 cosA cosB]
= cos²A - cos(A+B) cos(A-B)
= Cos²A - cos²A + sin²B
= Sun²B
Regards
Arun (askIITians forum expert)
Approved Last Activity: 7 Years ago
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