Answer:
≈39.27 units
Step-by-step explanation:
To find the area of a semi circle, you use the formula for finding the area of a circle, which is 
, and then you divide that by 2 since it is half of a circle.
In this case, 
≈ 78.54
= 39.27
Answer: here is an example in the screenshot
it is A,B,C, or D
Step-by-step explanation:
For a given perimeter, the area will be maximized when all the sides are the same length, which makes it actually a square. A square is still a rectangle, though! So, if you know the perimeter, divide it by four to determine the length of each side. Then multiply the length times the width to get the area.
BTW U CAN USE A CALCULATOR
Answer:

Step-by-step explanation:
Given


Required
Eliminate a
Multiply the first equation by -4

Add to the second equation

Solve brackets

Open bracket


At this point, a has been eliminated;
From the list of given options, the option that answers the question is 
C. Euclid is known as the father of Geometry
Answer:
No not all of them.
Step-by-step explanation:
Triangles can be 2d meaning like a flat triangle.