Question

solve the question 6 b please ​

Answer 1

Answer:

HEYA MATE HERE'S YOUR REQUIRED ANSWER PLEASE SEE THE ATTACHMENT ABOVE! If you didn't understand pls comment below and hope it helps..☺️

Answer 2

$HEYA \:$

SOME T- FORMULA!

1) Cos A + Cos B =

2 { Cos ( A + B )/2 × Cos ( A - B )/2 }

2) Cos A - Cos B =

-2 { Sin ( A + B )/2 × Sin ( A - B )/2

3) Cos 3A = 4 Cos³A - 3 Cos A

=>

L.H.S

Cos 10A + Cos 8A + 3 Cos 4A + 3 Cos2A

2 {(Cos 9A × Cos A) + 3( Cos 3A× CosA)}

2Cos A { Cos 9A + 3 Cos 3A }

2Cos A { Cos 3(3A) + 3 Cos 3A }

2Cos A{4 Cos³ 3A - 3 Cos 3A + 3 Cos3A}

= 8 × Cos A × Cos³ 3A

HENCE PROVED