What is the frequency of the sinusoidal graph?

The frequency is defined as

where is the period, i.e. the time between two maximum/minimum points.

In your example, you can see that a maximum is reached when , and the next one at . This means that the period is

So, the frequency is

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -

but there’s no any figure there!