Posted by **shan** on Wednesday, April 16, 2008 at 12:01am.

solve the following trig equation :

7 = 8sin(1/2)x. I can solve this using the half-angle indentity. But i need to solve this using period and phase change equation. how do i do this?

- math -
**Reiny**, Wednesday, April 16, 2008 at 8:39am
7 = 8sin(1/2)x

sin (1/2)x = .875

so (1/2)x is in the first or second quadrant, and

(1/2)x = 61.04º or (1/2)x = 118.96º

**then x = 237.9º or 122.1º**

but the period of your curve is 720º

so by adding/subtractin 720º to/from any of the found angles will give you more answers.

in general

x = 122.1 + 720k or

x = 237.9 + 720k , where k is an integer.

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