Consider the following two cosine equations.

MATHEMATICS · Multi-part · A Level · Mathematics · Trigonometry · Trigonometry

Problem

Consider the following two cosine equations. (i) Show that the equation

\cos \theta = \dfrac{3}{2}

has no real solution. (ii) Solve

\cos \theta = -\dfrac{1}{2}

for all values of

\theta

in the interval

[0,\,2\pi)

. (iii) Hence, write the general solution of

\cos \theta = -\dfrac{1}{2}