## dakid91 Group Title Use the double angle formula to rewrite the equation y = 4sin^2 (slashed zero) - 2. 2 years ago 2 years ago

1. tdabboud Group Title

is the slashed zero theta?

2. dakid91 Group Title

Yes.

3. tdabboud Group Title

it reduces to $y = -2 \cos(2\theta)$

4. dakid91 Group Title

Can you show me how it works?

5. tdabboud Group Title

You need to simply use that cos(2A) = 1- 2 sin^2(A)

6. tdabboud Group Title

so from this we take theta to be A

7. tdabboud Group Title

if you rewrite the equation you gave in that form it becomes.. -2 + 4sin^2(A)

8. tdabboud Group Title

from here we can factor out a -2 which leaves us with -2(1-2sin^2(A)) and you can see that the values under the parenthesis is just cos(2A) from the identity. So the answer you end up with after plugging in theta for A, is just -2cos(2Theta)

9. tdabboud Group Title

do you understand?

10. dakid91 Group Title

Yes. Thank you for giving a detailed explanation.

11. tdabboud Group Title

yeah no problem, glad i could help