(1 + sin x)(1 – sin x) = cos^2x

(1 + sin x)(1 – sin x) = cos^2x

1 - sin^2x = cos^2x

cos^2x = cos^2x

Step-by-step explanation:

Simplify the left hand side:

(1 + sin x)(1 – sin x) = cos^2x

1 - sin^2x = cos^2x

Using the Pythagorean Identity, we can see that the two sides are equivalent if you subtract sin^2x from both sides:

sin^2x + cos^2x = 1

cos^2x = 1 - sin^2x

Lastly, write it out:

(1 + sin x)(1 – sin x) = cos^2x

1 - sin^2x = cos^2x

cos^2x = cos^2x

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.