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

1. jennyjewell25

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

2. sabika13

i have to prove it using trigonometric identity without a calculator

3. wio

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

4. sabika13

what do i do with the leading coefficients?

5. wio

Factor them out.

6. wio

What did you get?