Which one of the following ordered pairs can represent for some real angle ?

MATHEMATICS · Single correct · AP · AP Precalculus · Trigonometric and Polar Functions · Trigonometric and Polar Functions

Problem

Which one of the following ordered pairs can represent

(\sin\theta,\cos\theta)

for some real angle

\theta

? (a)

(0.6,\,0.4)

(b)

\left(-\dfrac{\sqrt2}{2},\,\dfrac{\sqrt2}{2}\right)

(c)

(0.7,\,0.7)

(d)

\left(\dfrac{\sqrt3}{2},\,\dfrac{\sqrt2}{2}\right)