Ray

OC

divides ∠AOB into two angles. Find the measurement of ∠AOC, if m∠AOB = 155°, and m∠AOC is by 15° greater than m∠COB.

We are given that:

m∠AOB = m∠AOC + m∠COB

We are also given that:

m∠AOC = m∠COB + 15

m∠AOB = 155

Therefore:

155 = m∠COB + 15 + m∠COB

2 m∠COB = 140

m∠COB = 70°

and,

m∠AOC = m∠COB + 15 = 85°

Answers:

m∠COB = 70°

m∠AOC = 85 °