Posted by Victoria on Sunday, March 6, 2011 at 12:13pm.
if theta is an angle in standard position and B(3,4) is a point on the terminal side of the angle, what is the value of sin theta?

trig  Henry, Sunday, March 6, 2011 at 8:49pm
B(3,4), Q2.
r^2 = (3)^2 + 4^2 = 25,
r = 5.
sinAr = Y/r= 4 / 5 = 0.8,
Ar = 53.1deg = reference angle.
sinAr = Y/r = 4 / 5 = 0.80,
Since the angle is in Q2,the angle
calculated is actually the ref angle
which has the same trig ratios as the
actual angle. The actual angle is:
A = 180  Ar = 180  53.1 = 126.9deg.
sin126.9 = 0.8 = sin53.1.