Question

at about A = 90°7 Well, tan
for all A such that 0°SA
C. We get
A
for A = 0°. Therefore (4)
trigonometric ratio in ter
s known, we can also det
e identities. Suppose we
2
دا لاره
13
and cos A=
2​

Answer 1

Answer:

Solve the equation sin θ = − in the range, 0° ≤ θ ≤ 720°. We will now think of the trigonometric ratios as functions. Thus, the function y = sin θ has input values θ, consisting of angles, initially in the range 0° to 360°, and output values that are real numbers between −1 and 1.

Answer 2

Since the length OQ = cos θ is the x-coordinate of P, and PQ = sin θ is the y-coordinate of P, we see that the point P has coordinates

(cos θ, sin θ).

We measure angles anticlockwise from OA and call these positive angles. Angles measured clockwise from OA are called negative angles. For the time being we will concentrate on positive angles between 0° and 360°.

Since each angle θ determines a point P on the unit circle, we will define

the cosine of θ to be the x-coordinate of the point P

the sine of θ to be the y-coordinate of the point P.