Answer:

Step-by-step explanation:

Let's take one of the equations and solve for x. I'll take the first one.

Divide by 13.

Now replace x in the second equation.

Distribute -8

Break down the fraction.

Subtract 

Subtract 6y

Combine like terms;

Solve;

Keep solving;

Multiply by the negative reciprocal of the fraction next to y.

On the right side; 13 and 13 become 1. 300/30 = 30/3 = 10

After having found y, replace it in any of the equations to find x.

Answer: cos(Θ) = (√15) / 4
Explanation:
The question states:
1) sin(Θ) = 1/4
2) 0 < Θ < π / 2
3) find cos(Θ)
This is how you solve it.
1) Use the fundamental identity (in this part I use α instead of Θ, just for facility of wirting the symbols, but they mean the same for the case).

2) From which you can find:

3) Replace sin(α) with 1/4
=>

=>

4) Given that the angle is in the first quadrant, you know that cosine is positive and the final answer is:
cos(Θ) =

.
And that is the answer.
Answer:
a. (x + 4)² + (y – 7)² = 3²
Step-by-step explanation:
General equation for a circle is:
(x – h)² + (y – k)² = r²
h and k are the center (h, k), and r is the radius.
They want a center of (-4, 7) so h=-4 and k=7
They want a radius of 3 so r=3
plug it into the equation.
(x – h)² + (y – k)² = r²
(x – (-4))² + (y – (7))² = (3)²
(x + 4)² + (y – 7)² = 3²
You are correct there's at least one obtuse angle