Trigonometry Examples

$\cos (\frac{7 π}{4}) \cos (\frac{π}{7}) + \sin (\frac{7 π}{4}) \sin (\frac{π}{7}) = - \frac{\sqrt{2}}{2}$

Step 1

The left side $0.33027906$ does not equal to the right side $- 0.70710678$ , which means that the given statement is false.

False