This looks like a system of equations:
We should solve for c on the first equation because we can substitute for c. There are a lot of ways we can do a system of equations, but I will do this.
c - 3d = 11
+3d +3d
c = 11 +3d
Now we can substitute.
-2(11+3d) + 3d = -16
solve
-22 + -6d + 3d = -16
-22 + -3d = -16
+22 +22
-3d = 6
/-3 /-3
d = -2
So we have found d. We can solve for c.
c - 3(-2) = 11
c + 6 = 11
-6 -6
c = 5
Now we know both D and C. d=-2 and c=5

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9² = 12² + 15² - 2 (12) (15) cos (B)
81 = 144 + 225 - 360 cos(B)
81 = 369 - 360 cos (B)
360 cos (B) = 369 - 81
360 cos (B) = 288
cos (B) = 0.8
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Answer: Cosine B = 0.8
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12² = 15² + 9² - 2 (15)(9) cos (A)
144 = 225 + 81 - 270 Cos A
144 = 306 - 270 Cos A
270 Cos A = 162
Cos A = 3/5 or 0.6
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Answer: Cosine Angle A = 3/5
Answer:
I'm not so sure on these answers
1) 60 combinations
2) 90 or 60 combinations
Step-by-step explanation:
When doing these types of questions, use the Fundamental Counting Principle (you could also use a tree diagram which lists every possible combination individually for each item)
Basically for Fundamental Counting Principle, you multiply the amounts.
Ex: 5 jeans x 4 T-Shirts = 20 5 x 4 x 3 = 60!
20 x 3 pairs of shoes= 60
I wasn't sure if I had to include the right, left, right as 2 or 3.
Answer:
r=ts/-qu
Step-by-step explanation: