Answer:
Step-by-step explanation:
Comment
This uses the cosine Law for line length.
Formula
a^2 = b^2 + c^2 - 2*b*c*sin(A)
Givens
a = 5
b = 7
c = 10
Solution
5^2 = 7^2 + 10^2 - 2*7*10*cos(A)
25 = 49 + 100 - 140*cos(A) Combine the right side
25 = 149 - 140 * cos(A) Subtract 149 from both sides
25 - 149 = - 140*cos(A)
-124 = -140 * cos(A) Divide both sides by -140
-124/-140 = cos(A)
Cos(A) = 0.8857 Take the inverse Cos of both sides
A = cos-1(0.8857)
Answer
A = 27.66 degrees
