Question

in the figure below, what is the value of a?

a 30
b 50
c 60
d 70

Explanation:

Step1: Use the full - circle angle property

The sum of angles around a point is \(360^{\circ}\). Here, \(a + 11a=360\) (since the two angles \(a^{\circ}\) and \(11a^{\circ}\) make up a full - circle).

Step2: Solve the equation

Combine like terms: \(12a = 360\).
Divide both sides by 12: \(a=\frac{360}{12}\).

Answer:

\(a = 30\), so the answer is A. 30