Question

the diagram shows a triangle.
what is the value of a?
a = \square^\circ

Explanation:

Step1: Recall triangle angle sum

The sum of angles in a triangle is \(180^\circ\). So, \(12a + 42 + 30 = 180\).

Step2: Simplify the equation

Combine like terms: \(12a + 72 = 180\). Subtract 72 from both sides: \(12a = 180 - 72 = 108\).

Step3: Solve for \(a\)

Divide both sides by 12: \(a = \frac{108}{12} = 9\).

Answer:

\(a = 9\)