Answer:
A = (90°, 1)
B = (270°,-1)
Explanation:
if we don't use a calculator, we can explain by reasoning.
Observation 1:
recall y=sin x and y=cos x take values between -1 ≤ y ≤ 1, hence we know that the largest possible value for both functions is 1 and the smallest possible value is -1.
Observation 2:
we also know that both sin and cos functions are cyclic, which means that at some point, the function repeats itself every 360 degrees.
in question 1, we see that point A is located at the top most part of the curve, by observation 1, we can conclude that the y-value must be the maximum value of 1.
We also see that point A is 1/4 of the distance between the starting point of the curve at x=0 and to the end of the curve at x=360 before the curve begins to repeat itself,
hence the x - value is 1/4 of 360 = 90 degrees
Similarly, for point B, we see that B is at the lowest point of the curve, hence by observation 1, we can say that at B, y = -1.
B is also 3/4 of the distance between the start point and the end of the curve before it repeats itself,
hence the x-value of B is 3/4 x 360 = 270 degrees