X= -135°, cos 2x =

1 - 2 sin^2 x
1 - 2 sin x
1 + 2 sin^2 x
1 + 2 sin x

cos 2 x=1-sin^2 x

Step-by-step explanation:

x=-135°

cos 2x=cos (-270)=cos (-270+360)=cos 90=0

or cos 2x=1-2sin ²x=1-2(sin (-135))²

=1-2(-sin 135)²

=1-2(sin 135)²

=1-2(sin (180-45))²

=1-2(sin²45)

=1-2 (\frac{1}{\sqrt{2}})²

=1-1

=0

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.

this may not be at all, but i use the same website you're using for school, and if i'm stuck doing one of these i try to look for it on the section.