Question

Prove That :
____________

Answer 1

what

Answer 2

what

Answer 3

QED

Answer 4

\[2\cos(45-2A)\cos(45+2A)=1-8(\sin ^{2}A)(\cos ^{2}A)\]

Answer 5

ohhhhh my god

Answer 6

degrees? Or radians?

Answer 7

degrees

Answer 8

but it is easy i think because
cos(45-2A)=cos(45)*cos(A)+sin(45)*sin(A)=cos45cos2A+sin45sin2A.
COS(45+2A)=cos45cos2A-sin45sin2A.
cos(45-2A)cos(45+2A)=(cos45.*cos2A+sin45*sin2A)*(cos45cos2A-sin45sin2A.)= \[\cos ^{2}45\]*\[\cos ^{2}2A\]-\[\sin ^{2}45*\sin ^{2}2A\]=0.5*\[\cos ^{2}2A\]-0.5*\[\sin ^{2}2A\]
when we multiplay by 2 we find

Answer 9

i feel so tired you can complete