examday

Official papers

Official 2020 Paper 2 · Q15

Paper 2Logic & proofTrigonometrySequences & series

Which one of the following is a necessary and sufficient condition for

∑k=1nsin⁡(kπ3)=32\sum_{k=1}^n\sin\left(\frac{k\pi}3\right)=\frac{\sqrt3}2

to be true?

An=1n=1
Bnn is a multiple of 3
Cnn is a multiple of 6
Dnn is 1 more than a multiple of 3
Enn is 1 more than a multiple of 6
Fnn is 1 more than a multiple of 6 or nn is 2 more than a multiple of 6

Read the questions freely. Sign in to check your answer, see the worked solution and save your progress.

Sign in to check your answerPractise the whole paper →