# What is the frequency of #f(theta)= sin 6 t - cos 21 t #?

##### 1 Answer

Aug 12, 2016

#### Explanation:

The period for both sin kt and cos kt is

The periods for the separate oscillations

Twice the first is seven times the second. This common value

(least) # P = (2pi)/3) is the period for the compounded oscillation f(t).

See how it works.

#=f(t).

Note that P/2 used instead of P changes the sign of the second

term. .

Frequency is 1/P..