Well first find the area of the semi-circle.
If the area of a cricle is equal to pi*radius^2 , then you can just find that and divide by 2.
So, A = pi*2^2. = 4pi
We know that the radius is 2 because the length of the side of the rectangle is 4, meaning that the diameter of the semi-circle is 4, and so the radius is 2 as it is half of the diameter.
We can easily calculate the area of the rectangle, which is
Length * width = 6*4 = 24.
Next we divide 4pi by 2 in order to get the area of the semi-circle, giving us an area of 2pi
We can just subtract 2pi from 24 and get the area of the shaded region.
Area of the shaded region (answer): 17.7
So to solve for x, you'll need to combine all the angles and equal it to 720, and from there we can solve.

Combine like terms to get

Subtract 470 on each side to get

Then just divide on each side and you'll get

To find the value of the (x+10) angle, just substitute 125 for x and solve.
3pi/4 is 135 in degrees. A 135-degree angle lies in quadrant 2. In quadrant 2, the x values are negative and the y values are positive.