missbdoll 2 years ago If sinA=5/6, where angle A is in Quadrant 1, find the exact value of sin (1/2A)

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1. Notamathgenius

1,172cm(2)

2. NoelGreco

I assume that's sin (.5A). There is a half-angle formula for sin.

3. missbdoll

4. ajprincess

$\cos^2A+\sin^2A=1$$\cos A=\sqrt{1-\sin^2A}$ From this $$\cos A$$ can be found u can find $$\cos A$$. Then use $\cos A=1-2\sin^2(\frac{ 1 }{ 2 }A)$$\sin \frac{ 1 }{ 2 }A=\sqrt{\frac{ 1-\cos A }{ 2 }}$ from this u can find $\sin \frac{ 1 }{2}A$ Does that help?

5. missbdoll

but do u have an answer?

6. Notamathgenius

Mine is at the very top

7. missbdoll

did u use the half-angle formula because i'm getting a radical?

8. ajprincess

what r u getting?

9. missbdoll

|dw:1364227944196:dw|

10. ajprincess

|dw:1364228079352:dw||dw:1364228136955:dw| |dw:1364228182827:dw|

11. ajprincess

getting it?

12. missbdoll

13. ajprincess

yup

14. missbdoll

ok thank you so much

15. ajprincess

Welcome:) do u get it?

16. missbdoll

yes :)