Let A, B, C, D, E represent vertices of a regular pentagon ABCDE

MATHEMATICS · Single correct · CBSE · Mathematics · Vector Algebra · Vector Algebra

Problem

Let A, B, C, D, E represent vertices of a regular pentagon ABCDE. Given the position vector of these vertices be

a

a + b

\lambda a

and

\lambda b

respectively. The ratio

\frac{AD}{BC}

is equal to (1)

1 - \cos \frac{3\pi}{5} : \cos \frac{3\pi}{5}

(2)

1 + 2 \cos \frac{2\pi}{5} : \cos \frac{\pi}{5}

(3)

1 + 2 \cos \frac{\pi}{5} : 2 \cos \frac{\pi}{5}

(4) None of these