Typeâ3: Finding Angle Between Clock Hands (Angle / āĻā§āĻŖ āύāĻŋā§°ā§āĻŖāϝāĻŧ)
Rule (āύāĻŋāϝāĻŧāĻŽ): Angle (θ) = |30H − 11M/2|
• Where: H = Hour (āĻāĻŖā§āĻāĻž), M = Minute (āĻŽāĻŋāύāĻŋāĻ), θ = Angle between the two hands (āĻĻā§āϝāĻŧā§āĻāĻž āĻāĻžāĻāĻāĻžā§° āĻŽāĻžāĻā§° āĻā§āĻŖ)
Important Values (āĻā§ā§°ā§āϤā§āĻŦāĻĒā§āϰā§āĻŖ āĻŽāĻžāύ)
- Hour hand moves 30° per hour (āĻāĻŖā§āĻāĻžā§° āĻāĻžāĻāĻāĻž āĻĒā§ā§°āϤāĻŋ āĻāĻŖā§āĻāĻžāϤ 30° āĻāĻāĻŦāĻžāĻĸāĻŧā§āĨ¤)
- Relative movement = 11/2° per minute.. (āĻāĻĒā§āĻā§āώāĻŋāĻ āĻāϤāĻŋ = 11/2° āĻĒā§ā§°āϤāĻŋ āĻŽāĻŋāύāĻŋāĻāĨ¤)
Ex: Q. What is the angle between the two hands at 7:30 ? (āĻĒā§ā§°āĻļā§āύ: 7:30 āĻŦāĻāĻžāϤ āĻĻā§āϝāĻŧā§āĻāĻž āĻāĻžāĻāĻāĻžā§° āĻŽāĻžāĻā§° āĻā§āĻŖ āĻāĻŋāĻŽāĻžāύ ?)
Soln (āϏāĻŽāĻžāϧāĻžāύ)
• Here (āĻāϝāĻŧāĻžāϤ), H = 7 and(āĻāϝāĻŧāĻžāϤ) M = 30
• Apply the formula: θ = |30H − 11M/2|
θ = |30(7) − (11 × 30)/2|
θ = |210 − 165|
θ = 45°
Ans (āĻāϤā§āϤ⧰): Angle = 45°
7:30 āĻŦāĻāĻžāϤ āĻĻā§āϝāĻŧā§āĻāĻž āĻāĻžāĻāĻāĻžā§° āĻŽāĻžāĻā§° āĻā§āĻŖ = 45°
Main Points (āĻā§ā§°ā§āϤā§āĻŦāĻĒā§āϰā§āĻŖ āĻāĻĨāĻž)
- Use θ = |30H − 11M/2| to find the angle. (āĻā§āĻŖ āĻāϞāĻŋāϝāĻŧāĻžāĻŦāϞ⧠θ = |30H − 11M/2| āϏā§āϤā§ā§° āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻā§°āĻāĨ¤)
- Always take the positive value (absolute value).(āϏāĻĻāĻžāϝāĻŧ āϧāύāĻžāϤā§āĻŽāĻ āĻŽāĻžāύ (Absolute Value) āϞāĻāĻāĨ¤)
- If asked for the smaller angle, the answer must be less than or equal to 180°. (āϏ⧰⧠āĻā§āĻŖ āĻŦāĻŋāĻāĻžā§°āĻŋāϞ⧠āĻāϤā§āϤ⧰ 180° āĻŦāĻž āϤāĻžāϤāĻā§ āĻāĻŽ āĻš’āĻŦ āϞāĻžāĻāĻŋāĻŦāĨ¤)