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junior college 1 | H2 Maths
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junior college 1 chevron_right H2 Maths chevron_right Singapore

pls help asap

Date Posted: 1 year ago
Views: 249
EPQP
EPQP
1 year ago
50 = rθ + 2r

θ = 50/r - 2
dθ/dt = -50/r² × dr/dt = -50/10² × -5 = 5/2 radians per second.

A = 1/2r²θ = 1/2 r²(50/r - 2) = 25r - r²
dA/dt = (25 - 2r) × dr/dt = 5 × -5 = -25 cm² per second.

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Wee Wen Shih
Wee Wen Shih's answer
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Wee Wen Shih
Wee Wen Shih
1 year ago
Implicit differentiation approach :)
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Yap Cheong Sheng
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Hi, every time I see a differentiation question with respect to time, I immediately try to express the required thing (d0/dt) as a product or division of two other things (d0/dr * dr/dt).
Although treating the two things like fractions isn't right, it helps in solving these type of questions.