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secondary 4 | A Maths
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John tay
John Tay

secondary 4 chevron_right A Maths chevron_right Singapore

Pls help with qns 14

Date Posted: 1 month ago
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Eric Nicholas K
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J
J
1 month ago
Lol this question again
J
J
1 month ago
Alternative for ii)

When t = 3, the hour hand is horizontal and pointing rightwards.

The hand at this position makes an angle of π/2 rad with its previous position at the 12am mark.


Then h = 25

25 = 5(5 - 2 cos kt) = 25 - 10 cos kt

10 cos kt = 0 → coskt = 0

kt = π/2 rad

(We do not pick other bigger angles as the angle change from the 12am mark is not obtuse/is the magnitude of a right angle)


Since t = 3hr

3k hr = π/2 rad

k = π/6 rad/h
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