Recall the sum identity for cosine:
cos(a + b) = cos(a) cos(b) - sin(a) sin(b)
so that
cos(a + b) = 12/13 cos(a) - 8/17 sin(b)
Since both a and b terminate in the first quadrant, we know that both cos(a) and sin(b) are positive. Then using the Pythagorean identity,
cos²(a) + sin²(a) = 1 ⇒ cos(a) = √(1 - sin²(a)) = 15/17
cos²(b) + sin²(b) = 1 ⇒ sin(b) = √(1 - cos²(b)) = 5/13
Then
cos(a + b) = 12/13 • 15/17 - 8/17 • 5/13 = 140/221
Answer:
1/15 gal / mile if your numbers are correct
Step-by-step explanation:
1/5 / 15/4 = 1/5 * 4 / 15 = 4/60 = 1/15
Answer: c
Step-by-step explanation:
That is correct I think it is
Answer:
Step-by-step explanation:
To evaluate :
Solution:
Two negatives multiply to become a positive.
Thus, we can remove parenthesis by reversing the signs of the fraction by multiplying the negative outside.
⇒ 
Since the denominators are same for both fractions, so we simply add the numerators.
⇒ 
⇒ 
(Answer)
