Example 3: Time when clock hands are at right angles
Last Updated On: Sat Aug 29 2026Given Data
- Time interval: Between 2 o'clock and 3 o'clock.
- Target angle: 90 degrees.
Question
At what time between 2 and 3 o'clock are the hands of a clock at right angles?
Answer
27 3/11 minutes past 2.
Solution
- Set up the clock angle formula: |30H - 5.5M| = 90.
- Substitute H = 2: |30(2) - 5.5M| = 90 => |60 - 5.5M| = 90.
- Solving 5.5M - 60 = 90 gives 5.5M = 150.
- M = 150 / 5.5 = 300 / 11 = 27 3/11 minutes.
- Therefore, the hands form a right angle at 27 3/11 minutes past 2.