2sin^{2}B + 4cos\left (A +B \right )sinAsinB + cos2(A+B) =

Answers (1)
M manish

2sin^{2}B + 4cos\left (A +B \right )sinAsinB + cos2(A+B)
\Rightarrow 2\sin^2B + 4\cos (A+B)\sin A. \sin B+2\cos^2(A+B) -1 [by using the relation of \Right\cos 2\theta =\cos^2\theta -1]
\Rightarrow 2\sin^2B-1 +2\cos (A+B)[2\sin A.\sin B+\cos (A+B)] 
[using the formula of \cos (A+B) = \cos A.\cos B-\sin A.\sin B]

\Rightarrow 2\sin^2B-1 +2\cos (A+B)[2\sin A.\sin B+\cos A.\cos B -\sin A.\sin B]
\Rightarrow 2\sin^2B-1 +2\cos (A+B)(\cos (A-B))
\Rightarrow 2\sin^2B-1 +2\cos^2A -2\sin^2B
\Rightarrow 2\cos^2A-1 = \cos 2A


 

Preparation Products

Foundation 2021 Class 10th Maths

Master Maths with "Foundation course for class 10th" -AI Enabled Personalized Coaching -200+ Video lectures -Chapter-wise tests.

₹ 350/- ₹ 112/-
Buy Now
Knockout JEE Main April 2021 (One Month)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 14000/- ₹ 6999/-
Buy Now
Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
Buy Now
Test Series JEE Main April 2021

Take chapter-wise, subject-wise and Complete syllabus mock tests and get in depth analysis of your test..

₹ 6999/- ₹ 4999/-
Buy Now
Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-
Buy Now
Boost your Preparation for JEE Main 2021 with Personlized Coaching
 
Exams
Articles
Questions