Answer:
Step-by-step explanation:
Remark
a is one part of the cosine function. It is termed the adjacent side. The given number (12) is the hypotenuse of a right triangle. The reference angle is given as 25. You have all you need to solve for a
Givens
<B = 25o
AB = 12
a = a
Equation
Cos(B) = adjacent side / hypotenuse
Solution
Cos(25) = adjacent side / 12 Multiply both sides by 12
12*cos(25) = adjacent side
cos(25) = 0.90631
12*0.906331 = adjacent side
10.87 = adjacent side
Answer
a = 10.9
