if cos x = 3/8 what is sin x?

Question

whpalmer4 · Answer

Use the trig identity 
$$\cos^2{x} + \sin^2{x} = 1$$

whpalmer4 · Answer

Remember that sin, cos are defined in terms of that unit circle, so the hypotenuse is always 1, and the sides of the right triangle are sin and cos

anonymous · Answer

Alright, thanks.

anonymous · Answer

Though it's been like 2 years since I've done this...

anonymous · Answer

I ended up with like x coming to be .002454334215773

anonymous · Answer

and plugged it into the trig identity equation and got very close to one, so I assume that's the correct answer.

whpalmer4 · Answer

attachment

whpalmer4 · Answer

Let's work it out.
$$\cos{x} = 3/8$$$$\cos^2x+\sin^2x = 1$$$$(3/8)^2+\sin^2x = 1$$$$\sin^2x = \frac{64}{64}-\frac{9}{64}$$$$\sin x=\frac{\sqrt{55}}{8} \approx 0.927 $$

whpalmer4 · Answer

If you did this with a calculator, is your calculator expecting degrees, or radians for trig functions?  The identity applies to radians, not degrees.

whpalmer4 · Answer

@modestgengar

anonymous · Answer

I forgot to divide by 8...that's where I went wrong.