Question

H E L P :
Cos (13pi/12 ) Use Half Angle ID to simplify ~

Answer 1

I got : -root 3 - root 6 / 4 Is that what you got..?

Answer 2

radian or degree?

Answer 3

What do you mean? You just use that ID to simplify?

Answer 4

but i dont what ID.

Answer 5

\[\Large \cos\left(\frac{13\pi}{12}\right) = \cos\left(\frac{1}{2}\cdot\frac{13\pi}{6}\right)\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\sqrt{\frac{1+\cos\left(\cdot\frac{13\pi}{6}\right)}{2}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\sqrt{\frac{1+\frac{\sqrt{3}}{2}}{2}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\sqrt{\frac{1}{2}+\frac{\sqrt{3}}{4}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\sqrt{\frac{2}{4}+\frac{\sqrt{3}}{4}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\sqrt{\frac{2+\sqrt{3}}{4}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\frac{\sqrt{2+\sqrt{3}}}{\sqrt{4}}\]


\[\Large \cos\left(\frac{13\pi}{12}\right) = -\frac{\sqrt{2+\sqrt{3}}}{2}\]

Answer 6

cool thnx! (:

Answer 7

yw