WAEC Mathematics Past Questions & Answers - Page 122

606.

Given that cos xo = \(\frac{1}{r}\), express tan x in terms of r

A.

\(\frac{1}{\sqrt{r}}\)

B.

\(\sqrt{r}\)

C.

\(\sqrt{r^2 + 1}\)

D.

\(\sqrt{r^2 - 1}\)

Correct answer is D

cos xo = \(\frac{1}{r}\); \(\sqrt{r^2 - 1}\)

By Pythagoras r2 = 12 + x2 - 1

x = \(\sqrt{r^2 - 1}\)

tan xo = \(\sqrt{r^2 - 1}\)

= \(\sqrt{r^2 - 1}\)

607.

Solve for x in the equation; \(\frac{3}{5}\)(2x - 1) = \(\frac{1}{4}\)(5x - 3)

A.

zero

B.

1

C.

2

D.

3

Correct answer is D

\(\frac{3}{5}\)(2x - 1) = \(\frac{1}{4}\)(5x - 3)

\(\frac{6x}{5} - \frac{3}{5} = \frac{5x}{4} - \frac{3}{4}\)

\(\frac{6x}{5} - \frac{5x}{4} = \frac{3}{5} - \frac{3}{4}\)

\(\frac{24x - 25x}{20} = \frac{12 - 15}{20}\)

\(\frac{-x}{20} = \frac{-3}{20}\)

-20x = -60

x = \(\frac{-60}{-20}\)

x = 3

608.

If N112.00 exchanges for D14.95, calculate the value of D1.00 in naira

A.

0.13

B.

7.49

C.

8.00

D.

13.00

Correct answer is B

D14.95 = N112.00

D1.00 = \(\frac{N112}{D14.95} \times\) D1.00

= 7.49

609.

In the diagram, < WOX = 60o, < YOE = 50o and < OXY = 30o. What is the bearing of x from y?

A.

300o

B.

240o

C.

190o

D.

150o

Correct answer is A

The bearing of x from y = 270o + \(\theta\)

where \(\theta\) + 50o = y

in \(\bigtriangleup\) OXY

O + X + Y = 180o

Where O = 40o + 30o = 70o

70o + 30o + y = 180o

y + 100o = 180o

y = 180o - 100o = 30o

\(\theta\) + 50o = 80o

80o - 50o = 30o

The bearing of x from y = 270o + 30o = 300o

610.

In the diagram, 0 is the centre of the circle. Find the value x

A.

34

B.

29

C.

17

D.

14

Correct answer is D

POQ in a straight line

Hence, < POQ + < QOR = 180o

56o + < QOR = 180o

< QOR = 180o - 56o

= 124o

Now, in \(\bigtriangleup\) QOR OR = OQ = Radius

< ORQ = < OQR = 2x (Base angles of an Isosceles \(\bigtriangleup\))

2x + 124 + 2x = 180o

4x + 124 = 180

4x = 180 - 124

4x = 56

x = \(\frac{56}{4}\)

x = 14o