Help me with 3 and 4 please! Explain how you got your answer, i will give out Brainliest

3-

area=1×(5-3) + (4-1)×5=2+15=17

4-

area=4×6+3.14×(4÷2)²/2=30.24

6-

area= 12×8-3×4=84

7-

area= 8×18+3.14×1²/2=147.45

the square root of what number? if you add that, then someone will probably answer the question.