Posted by **Ama** on Sunday, October 28, 2012 at 11:55am.

Use a Double- or Half-Angle Formula to solve the equation in the interval [0, 2π). (Enter your answers as a comma-separated list. Round your answers to three decimal places where appropriate.)

sin 2θ + sin θ = 0

- precalculus -
**Steve**, Sunday, October 28, 2012 at 12:21pm
sin2x = 2sinx cosx

so, you have

2sinx cosx + sinx = 0

sinx (2cosx+1) = 0

you should be able to sort that out easily, looking for values where

sinx=0 or cosx = -1/2

- precalculus -
**Ama**, Sunday, October 28, 2012 at 1:07pm
If a projectile is fired with velocity v0 at an angle θ, then its range, the horizontal distance it travels (in feet), is modeled by the function

R(θ) =

v02 sin 2θ

32

.

If

v0 = 2600 ft/s,

what angle (in degrees) should be chosen for the projectile to hit a target on the ground 5000 ft away? (Enter your answers as a comma-separated list. Round your answers to three decimal places.)

Thanks.

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