Answer:
(a)
(b) 
Step-by-step explanation:
It is given that
.
(a)
(b)
![[\because \sin x=\dfrac{1}{\csc x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Csin%20x%3D%5Cdfrac%7B1%7D%7B%5Ccsc%20x%7D%5D)

Therefore,
.
Answer:
x = 8.45
Step-by-step explanation:
5.4 + 0.2x = 7.09
Subtract 5.4 from both sides to leave 0.2x alone
0.2x = 1.69
Divide by 0.2 on both sides to isolate x
x = 1.69/0.2
x = 8.45
I would go about solving this by elimination because the x variables are already the same so all you would have to do is change one equation to the opposite signs and add them, so it would look like:
7y + 5x = 19
+ -3y - 5x = -7
-------------------
4y=12
y=3
This is Pythagorean theorem, a^2+b^2=c^2 , a = 33 and c = 37 so b^2 + 1089 = 1369 , b^2 = 280 , b = 16.73m