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

is the slashed zero theta?

2. dakid91

Yes.

3. tdabboud

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

4. dakid91

Can you show me how it works?

5. tdabboud

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

6. tdabboud

so from this we take theta to be A

7. tdabboud

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

8. tdabboud

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

do you understand?

10. dakid91

Yes. Thank you for giving a detailed explanation.

11. tdabboud

yeah no problem, glad i could help