Question

Find the trigonometric functions of :

− 90°

Answer 1

Angle of measure (– 90°):

Let m∠XOA = 90°

Its terminal arm (ray OA) intersects the standard unit circle at P(0, −1).

∴ x = 0 and y = −1

sin (– 90°) = y = −1

cos (– 90°) = x = 0

tan (–90°) = `y/x = (-1)/0`,

which is not defined.

cosec (– 90°) = `1/y = 1/(-1)` = −1

sec (– 90°) = `1/x = 1/0`,

which is not defined.

cot (– 90°) = `x/y = 0/(-1)` = 0