Step-by-step explanation
b = 2h is given
2 b + h = 4 hours is given sub in the top equation
2 (2h) + h = 4
5h = 4
h = 4/5 hr or 48 minutes
Answer: C
Step-by-step explanation: They are never the same
First, lets note that

. This leads us with the following problem:

Lets add sin on both sides, and we get:

Now if we divide with sin on both sides we get:

Now we can remember how cot is defined, it is (cos/sin). So we have:

Now take the inverse of cot and we get:

In general we have

, the reason we have to add pi times n, is because it is a function that has multiple answers, see the picture:
Simply use the formula they give you. For question 6, 4 is the radius. So the area of the circle is 4pi. Now for seven you do the same thing, but they gave you the diameter instead and it’s a half circle. So try that one on your own. Let me know if you get stuck