MathCastle
TrigonometrySuperchallengeThe Unit Circle and Circular Functions

The Unit Circle and Circular Functions · Superchallenge problem

Let A=(1,0)A=(1,0), and for k=0,1,2,…,11k=0,1,2,\dots,11 let PkP_k be the terminal point on the unit circle of the angle kπ6\dfrac{k\pi}{6}. Find ∑k=011APk 2\displaystyle\sum_{k=0}^{11}AP_k^{\,2}, the sum of the squared distances from AA to the twelve points.