chaotic_butterflies one year ago Simplify (1 − sin x)(1 + sin x).

1. misty1212

HI!!

2. chaotic_butterflies

Hello

3. misty1212

multiply out you get $1-\sin^2(x)$

4. misty1212

then use a famous identity to rewrite it

5. chaotic_butterflies

Oh wow the first step was simple enough, but I'm not sure what you're talking about by a certain "famous identity"

6. misty1212

the mother of all trig identities is $\cos^2(x)+\sin^2(x)=1$ so $1-\sin^2(x)=\cos^2(x)$

7. geerky42

Aka Pythagorean Identity.

8. chaotic_butterflies

Okay, now I got it. Thank you very much! ^_^