Question

If the radius of circle D is 5, find AB. Round your answer to the nearest tenth.
6.8
7.7
8.1
8.6​

Answer 1

Answer:

The answer is option 2.

Step-by-step explanation:

Using Cosine Rule, c² = a²+b²-2(a)(b)cosθ where a,b and c represents the side length :

Let a = AD = 5 units (radius),

Let b = BD = 5 units (radius),

Let c = AB,

Let θ = 100°,

c² = 5² + 5² - 2(5)(5)cos 100°

c² = 50 - 50cos 100°

c² = 58.68

c = √58.68

= 7.7 units (near. tenth)