Question #891ae

1 Answer
Nov 7, 2017

One way is to substitute 45^\circ for x

Explanation:

Let x = 45^\circ

Cos(2*45^\circ)Cos(2*45^\circ)+3sin(2*45^\circ)=2+cos(4*45^\circ)

=cos(90^\circ)cos(90^\circ)+3sin(90^\circ)=2+cos(180^\circ)

cos(90^\circ)=0
sin(90^\circ)=1
cos(180^\circ)=0

0+3*1=2+0

3 \ne 2