Question

If arc CE = 40°, and m∠CDE = 30°, what is arc AB?

70°
100°
140°
20°

Answer 1

To solve this, use the same equation you would find to use to solve for the angle

\(m\angle CDE=\dfrac{far~arc-near~arc}{2}\) or \(m\angle CDE=\dfrac{arc~AB-arc~CE}{2}\)

We are solveing for AB (Let's substitute what we have)
AB = x

\(30=\dfrac{x-40}{2}\)

I assume you can solve from here