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:
108
Step-by-step explanation:
x=number
X
___. = 18
6
Multiply 6 on both sides to get X by itself
18x6=108
x=108
Answer:
20$ × 15 = 300
543- 300= 243
243÷ 27= 9
she sold 9 wreaths
Step-by-step explanation:
Answer:
sin xy / x = 0
Step-by-step explanation:
thay x = 0 và y = 3 vào sin xy / x ta có:
sin (0*3) / 0 = sin (0) = 0
Answer:
x = 10
y = 14
Step-by-step explanation:
Here, we want to get the values of x and y
Since all sides are equal, the internal angle is 60 degrees for each internal angle
Since AC = 14
Then y is also 14 since what we have is an equilateral triangle
Secondly ;
6x = 60
x = 60/6
x = 10
