## sabika13 Group Title how do i prove this using trig identity: (2sinx+3cosx)^2+(3sinx-2cosx)^2=13 one year ago one year ago

1. jennyjewell25 Group Title

i did this on my calculator type it in your calulator just as your type on here tell me what you get

2. sabika13 Group Title

i have to prove it using trigonometric identity without a calculator

3. wio Group Title

First, use foil to expand them. Then use the following identity $\sin^2(\theta)+\cos^2(\theta)=1$

4. sabika13 Group Title

what do i do with the leading coefficients?

5. wio Group Title

Factor them out.

6. wio Group Title

What did you get?