Question

-(1/4)=sinx solve for x. do I use special triangles?

Answer 1

x = Sin^-1(-1/4)

Answer 2

-14deg

Answer 3

no you use a calculator for this one

Answer 4

if it was (1/sqrt2)= sinx, i could use special triangles?

Answer 5

use expansion formula for sin inverse of x

Answer 6

If sinx - 1/4 = 0, you are looking for values of x where sinx = 0.25.

sinx is positive in the interval from 0 to pi (and zero at 0 and pi) and negative from pi to 2pi, so your solutions will be in the first interval.

So, check out arcsin0.25 in a table and look for values between 0 and 1.

Or, use an interesting fact about sinx, which is that for values of x near zero, sinx is nearly equal to x in this interval. That is why lim as x ->0 of sinx/x is one.

So, by symmetry, your answers are roughly 0.25 and pi - 0.25 (3.14-0.25 = 2.89)

Answer 7

ooh thanks hah thats really helpful :)