# MIE 2016/Day 1/Problem 4

### Problem 4

In the expansion of

$\left(x\sin2\beta+\frac{1}{x}\cos2\beta\right)^{10}$

the independent term (in other words, the term without $x$) is equal to $63/256$. With $\beta$ being a real number such that $0< \beta<\pi/8$ and $x\neq0$, the value of $\beta$ is:

(a) $\frac{\pi}{9}$

(b) $\frac{\pi}{12}$

(c) $\frac{\pi}{16}$

(d) $\frac{\pi}{18}$

(e) $\frac{\pi}{24}$

## Solution

&\tan(2b)= &\frac{1}{4}\\&