Math Problem Statement

find in degree&radians.The angel between the hands of the clock at the specified time 1.3:00 2.5:15 3.7:10 4.2:35 5.4:13

Solution

To find the angle between the hour and minute hands at any given time, we need to break down each component's movement on the clock face. The formula to calculate the angle is as follows:

  1. Hour Hand Movement: The hour hand moves 3030^\circ per hour (since 360/12=30360^\circ / 12 = 30^\circ).

    • Additionally, it moves 0.50.5^\circ per minute (30/6030^\circ / 60).
  2. Minute Hand Movement: The minute hand moves 66^\circ per minute (since 360/60=6360^\circ / 60 = 6^\circ).

General Formula

For a time given in hours (hh) and minutes (mm), the angle θ\theta between the hands of the clock can be calculated as: θ=(30×h+0.5×m)(6×m)\theta = |(30 \times h + 0.5 \times m) - (6 \times m)| If θ\theta exceeds 180180^\circ, we take 360θ360^\circ - \theta for the smallest angle.

Let's apply this formula to each time given.


1. Time: 3:00

  • Hour hand angle = 30×3+0.5×0=9030 \times 3 + 0.5 \times 0 = 90^\circ
  • Minute hand angle = 6×0=06 \times 0 = 0^\circ
  • θ=900=90\theta = |90 - 0| = 90^\circ

Answer: 9090^\circ or π2\frac{\pi}{2} radians.

2. Time: 5:15

  • Hour hand angle = 30×5+0.5×15=150+7.5=157.530 \times 5 + 0.5 \times 15 = 150 + 7.5 = 157.5^\circ
  • Minute hand angle = 6×15=906 \times 15 = 90^\circ
  • θ=157.590=67.5\theta = |157.5 - 90| = 67.5^\circ

Answer: 67.567.5^\circ or 9π24\frac{9\pi}{24} radians.

3. Time: 7:10

  • Hour hand angle = 30×7+0.5×10=210+5=21530 \times 7 + 0.5 \times 10 = 210 + 5 = 215^\circ
  • Minute hand angle = 6×10=606 \times 10 = 60^\circ
  • θ=21560=155\theta = |215 - 60| = 155^\circ

Answer: 155155^\circ or approximately 2.7052.705 radians.

4. Time: 2:35

  • Hour hand angle = 30×2+0.5×35=60+17.5=77.530 \times 2 + 0.5 \times 35 = 60 + 17.5 = 77.5^\circ
  • Minute hand angle = 6×35=2106 \times 35 = 210^\circ
  • θ=77.5210=132.5\theta = |77.5 - 210| = 132.5^\circ

Answer: 132.5132.5^\circ or approximately 2.312.31 radians.

5. Time: 4:13

  • Hour hand angle = 30×4+0.5×13=120+6.5=126.530 \times 4 + 0.5 \times 13 = 120 + 6.5 = 126.5^\circ
  • Minute hand angle = 6×13=786 \times 13 = 78^\circ
  • θ=126.578=48.5\theta = |126.5 - 78| = 48.5^\circ

Answer: 48.548.5^\circ or approximately 0.8460.846 radians.


Would you like more details on any of these steps or additional examples?

Related Questions

  1. What is the angle at 10:30?
  2. How can you calculate the angle for times with seconds?
  3. Why does the formula use 0.5 degrees per minute for the hour hand?
  4. How do we determine if we need the supplementary angle for times like 9:45?
  5. How does the angle calculation change on a 24-hour clock?

Tip: Always check if your angle exceeds 180 degrees to ensure you have the smallest angle.

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Math Problem Analysis

Mathematical Concepts

Clock Angle Problems
Geometry
Angular Measurement

Formulas

Angle between clock hands = |(30 * hour + 0.5 * minutes) - (6 * minutes)|
If angle > 180°, smallest angle = 360° - angle

Theorems

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Suitable Grade Level

Grades 7-10