If x a third quadrant angle and y an acute angle such that cos x=-(3/5) and sec y= (3/2) ,find the exact value of sin(x-y) , exact value of tan(x-y) and quadrant containing (x-y)?
1 Answer
Find sin (x - y), knowing cos x = -3/5 and sec y = 3/2
Explanation:
Apply the trig identity:
sin (x - y) = sin x.cos y - sin y.cos x
Apply trig identity:
The arc (x - y) is located in Quadrant III since its cos and its sin are both negative.
Check by calculator:
Arc (x - y) = 233.14 - 48.19 = 184.95 deg --> sin (x - y) = -0.09