Answer:
8√113 / 113
Step-by-step explanation:
Representing the information on a triangle :
From trigonometry :
Cos θ = Adjacent / hypotenus = AC / AB
AB = hypotenus :
Using Pythagoras :
AB² = AC² + BC²
AB² = 8² + (-7)²
AB² = 64 + 49
AB = √113
Cos θ = AC / AB = 8 / √113
RATIONALIZE :
8/√113 * √113/√113 = 8√113 / 113
