Answer:
The angle C measures 48.89°.
Explanation:
We use the Sine inverse trigonometric function to solve for C.
In a triangle the ratio of the side opposite to angle C, and the hypotenuse is given by the Sine function:

and for our angle C, the opposite is 55 and the hypotenuse is 73; thus

Now the inverse sine function gives back the angle C, if the ratio
is known, that is

We know that for angle C

therefore


Note that we did not use an equation when evaluating
that is because there isn't any: you have just got to use a calculator or memorize some values for the inverse sine function.