In a triangle with one angle

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

\frac{2\pi}{3}

, the lengths of the sides form an A.P. If the length of the greatest side is

7\ \text{cm}

, the radius of the circumcircle of the triangle is (1)

\frac{7\sqrt{3}}{3}\ \text{cm}

(2)

\frac{5\sqrt{3}}{3}\ \text{cm}

(3)

\frac{2\sqrt{3}}{3}\ \text{cm}

(4)

\sqrt{3}\ \text{cm}