Given:

To find:
The value of
.
Solution:
We know that,
...(i)
Where n is an integer.
We have,

Using (i), it can be written as


It is given that
.


Therefore, the value of the given function expression is
.
The interior angles of a triangle add up to 180 degrees
40 + 2x - 30 + x + 20 = 180
3x + 30 = 180
3x = 180 - 30
3x = 150
x = 150/3
x = 50
< A = 40
< B = 2x - 30.....2(50) - 30 = 70 <===
< C = x + 20......50 + 20 = 70