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At what time after 7:00 pm will the hands of the clock be opposite to each other? |
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Answer» Just at 7.00pm the hour hand is at 7 and minute hand is at 12. Each minute division makes 6∘ at the center. So at 7.00 pm a reflex angle of 210∘ will be formed between hour hand and minute hand because the hour hand will be at 35 minute divisions ahead of minute hand. Let x minute after 7.00pm the hands of the clock will be opposite to each other.Then the angle between the hands will be 180∘ We know hour hand rotates 360∘ in 12hr or 720 minutes So in x minute the hour hand will increase the reflex angle by 360x720=(x/2)∘ In this x minute the minute hand will decrease the reflex angle by (6x)∘ . Hence 210∘+(x/2)∘−(6x)∘=180∘ ⇒x=(60/11) minute So at 7 past 55/11minute the hands will become opposite to each other. |
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