(a) Two cyclists X and Y leave town Q at the same time. Cyclist X...

MATHEMATICS
WAEC 2020

(a) Two cyclists X and Y leave town Q at the same time. Cyclist X travels at the rate of 5 km/h on a bearing of 049° and cyclist Y travels at the rate of 9 km/h on a bearing of 319°.

(a) Illustrate the information on a diagram.

(b) After travelling for two hours, calculate. correct to the nearest whole number, the:

(i) distance between cyclist X and Y;

(ii) bearing of cyclist X from Y.

(c) Find the average speed at which cyclist X will get to Y in 4 hours.

Explanation

(b)(i) m\(^2\) = 5\(^2\) + 9\(^2\)

m\(^2\) = 25 + 81

m\(^2\) = 106

m = \(\sqrt{106}\) = 10.296 km/hr

Speed = \(\frac{distance}{times}\)

distance = speed x time

= 10.296 x 2

= 21km

(b)(ii)

tan\(\theta\) = \(\frac{9km/hr}{5km/hr}\)

tan\(\theta\) = 1.8

\(\theta\) = tan\(^{-1}\)

\(\theta\) = 60.9\(^o\)

the bearing of cyclist x from y

90\(^o\) + 19.9\(^o\) = 109.9\(^o\)

= 110\(^o\)

(c) The average speed = \(\frac{distance }{time}\)

= \(\frac{21}{4}\)km

= 5km/her



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