The first thing you need to do is find the radius of the semicircle. To do that you look to see that the width of the rectangle is the same as the radius. Once you have the Area of a Semicircle calculated multiply it by 3. then, we know that the other length of the rectangle is 3 diameters of a semicircle this means that you multiply the radius of 7 by 6 which gives you 42. You take the area of the rectangle (294) and subtract the area of the 3 semicircles(230.79) Which gives you the answer of 63.21cm^2
Since this is a right triangle, we can use one of the three main trigonometric functions: sine, cosine, tangent.
Remember: SOH-CAH-TOA
From the angle, we know the opposite side and want to figure out the adjacent side. Therefore, we should use the tangent function.
tan(35) = 6/RS
RS = 6 / tan(35)
RS = 8.6
Hope this helps!