Two angles A and B are 60°, 60°. What will be the third angle C?

Appeared in: RML PRE 2025

Explanation

The sum of the interior angles of any triangle is a constant value of 180°.
Given that two angles are 60° each, their combined sum is 60° + 60° = 120°.
To find the third angle, subtract this sum from the total of 180°: 180° - 120° = 60°.
A triangle where all three interior angles are 60° is known as an equilateral triangle.

Option B: This value represents the total sum of all three angles in any triangle, not the measure of a single unknown angle.
Option C: A 90° angle would make the triangle a right-angled triangle. In this case, the sum of the other two angles would have to be 90°, which is not true here (60° + 60° = 120°).
Option D: This is the sum of the two known angles (60° + 60°), not the value of the third, missing angle.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Sum of interior angles of a triangle as background academic context rather than a clinical decision trigger.
This question tests foundational knowledge in geometry, which is a part of the general aptitude section in nursing entrance exams.
While not a direct clinical skill, strong mathematical and logical reasoning abilities are essential for nurses in tasks like calculating drug dosages, interpreting patient data charts, and managing IV drip rates.
What if the two given angles were 90° and 30°? The third angle would be 180° - (90° + 30°) = 60°, forming a right-angled scalene triangle.

How to Approach the Question

First, identify the core concept being tested, which is the properties of a triangle's angles.
Recall the fundamental rule: the sum of the interior angles of any triangle always equals 180°.
Add the values of the two known angles provided in the question: 60° + 60° = 120°.
Subtract this sum from 180° to calculate the measure of the unknown third angle: 180° - 120° = 60°.
Compare your calculated result with the given options to select the correct answer.
Recognize that since all angles are 60°, the triangle is an equilateral triangle.

Concept Tested & Keywords

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Practise the full RML PRE 2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.