Question

two angles of a triangle are given below.
?°, 15°, 85°
find the measure of the 3rd angle.

Explanation:

Step1: Recall the sum of angles in a triangle

The sum of the interior angles of a triangle is \(180^{\circ}\). Let the unknown angle be \(x\). Then \(x + 15^{\circ}+85^{\circ}=180^{\circ}\).

Step2: Solve for \(x\)

Simplify the left - hand side: \(x+(15 + 85)^{\circ}=180^{\circ}\), so \(x + 100^{\circ}=180^{\circ}\). Subtract \(100^{\circ}\) from both sides: \(x=180^{\circ}-100^{\circ}\).

Answer:

\(80^{\circ}\)