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secondary 4 | A Maths
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Nelson Loo
Nelson Loo

secondary 4 chevron_right A Maths chevron_right Singapore

Anyone out there knows how to understand this question by plotting a trigo graph?

Date Posted: 3 years ago
Views: 336

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Boy Mow Chau
Boy Mow Chau's answer
316 answers (Tutor Details)
1st
for sine function of the form y = A sin Bx + C
A = amplitude
B = 2 pi / period
C = vertical shift

for (a), the question does not specify which direction the ferris wheel is turning. If the ferris wheel is turning in a clockwise direction, then the equation is …
y = 105 - 75 sin [(pi/15)t]
and the graph is inverted along the line y = 105.

for (b), each time the ferris wheel turns one complete round, there will be 2 occasions when the visitor is at 150 m. I am assuming that the question is asking for the 1st time that the visitor is at 150 m.

the 2nd time that the visitor is at 150 m is
15 - 3.07 = 11.93 mins

from the graph, you should be looking at the points where the curve intersects the line y = 150.