How do you calculate this without Calculator?

Geometry Level 4

8cos2π7(2cos22π7+cos2π71)+1=?8\cos \frac{2\pi}{7} \left( 2\cos^2 \frac{2\pi}7 +\cos \frac{2\pi}7 -1 \right) +1 = \, ?

×

Problem Loading...

Note Loading...

Set Loading...