Finally...
(1-sin x )(1+sin x )
Now we have (1-sin(x)) (1+sin(x))
There is something call Expanded which is the way to write numbers by showing the value of each digit (google)
So let's us it to see what we find.
(1-sin(x)) (1+sin(x) that's equal 1-sin²(x)
We knew that 1-sin²(x) = cos²(x)
Answer : Cos²(x)
wow I did it guys :))
Hey I hope its help XD