The three angles of a triangle are in the ratio 4 : 7 : 9. What is the measure of the greatest angle?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 81°
The angles of a triangle add up to \(180^\circ\), so the angles are \(4k\), \(7k\) and \(9k\) with \(20k=180^\circ\).
\(4k+7k+9k=20k=180^\circ\), so \(k=9^\circ\)
The angles are \(36^\circ\), \(63^\circ\) and \(81^\circ\)
Greatest angle \(=9\times9^\circ=81^\circ\)