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

answer: 40392

step-by-step explanation:

10098 x 4 = 40392

answer: cos [   arcsin (3/5) - arccos (1/2) ] =

step-by-step explanation: × = 3/5 = 0.6--> x = 36.87 and x = 180 - 36.87 = 143.13 deg

cos y = 1/2 --> y = +- 60 deg a. cos (x - y) = cos (143.13 - 60) = cos 83,13  

=

0.12

b. cos (36.87 - 60) = cos (-23.23) = 0.92