If x is an angle in standard position with point (6,-8) on its terminal side, find sin x. ?
- Wayne DeguManLv 74 months ago
Point (6, -8) is in quadrant IV where sinθ < 0
Also, we have a 6, 8, 10 triangle using Pythagoras' theorem.
so, sinθ = -8/10 => -0.8
- 4 months ago
They really should have used a different symbol for the angle, rather than x, but no matter. Let's call it t, shall we?
sin(t) = y / sqrt(x^2 + y^2)
That's all there is to it
y = -8
x = 6
sqrt(x^2 + y^2) = sqrt(36 + 64) = sqrt(100) = 10
sin(t) = -8 / 10 = -4/5
-4/5 is the answer.
See, if I had given you the definition for the sine of an angle and I had used "x" to denote the angle, then this is what you would have gotten:
sin(x) = y / sqrt(x^2 + y^2)
And that's just needlessly confusing. You should bring this up with your teacher.
-4/5 = -0.8