WAEC Mathematics Past Questions & Answers - Page 80

396.

The angle of elevation of an aircraft from a point K on the horizontal ground 30\(\alpha\). If the aircraft is 800m above the ground, how far is it from K?

A.

400.00m

B.

692.82m

C.

923.76m

D.

1,600.99m

Correct answer is D

In \(\bigtriangleup\)KBC, sin 30 = \(\frac{800}{IKCI}\)

IKCL = \(\frac{800}{sin30^o}\)

= \(\frac{800}{0.5}\)

= 1600m

397.

PQRT is square. If x is the midpoint of PQ, Calculate correct to the nearest degree, LPXS

A.

53o

B.

55o

C.

63o

D.

65o

Correct answer is C

In the diagram given,

tan\(\alpha\) = \(\frac{1}{0.5}\) = 2

\(\alpha\) = tan - 1(2) = 63.43o

= 63o

398.

\(\begin{array}{c|c}
x & 0 & 1\frac{1}{4} & 2 & 4\\
\hline
y & 3 & 5\frac{1}{2} & &
\end{array}\)
The table given shows some values for a linear graph. Find the gradient of the line

A.

1

B.

2

C.

3

D.

4

Correct answer is B

Ler: (x1, y1) = (0, 3)

(x2, y2) = (\(\frac{5}{4}, \frac{11}{2}\))

Using gradient, m = \(\frac{y_2 - y_2}{x_2 - x_1}\)

= \(\frac{\frac{11}{2} - 3}{\frac{5}{4} - 0}\)

= \(\frac{11 - 6}{2} + \frac{5}{4}\)

= \(\frac{5}{} + \frac{5}{4}\)

= \(\frac{5}{2} \times \frac{4}{5}\)

= 2

399.

In the diagram, O is the centre, \(\bar{RT}\) is a diameter, < PQT = 33\(^o\) and <TOS = 76\(^o\). Using the diagram, calculate the value of angle PTR.

A.

73o

B.

67o

C.

57o

D.

37o

Correct answer is C

In the diagram given, < PRT = 3\(^o\) (Change in same segment)

< TPR = 90\(^o\) (angle in a semicircle)

Hence, < PTR = 180\(^o\) - (90 + 33)\(^o\)

= 180\(^o\) - 123\(^o\)

= 57\(^o\)

400.

In the diagram, PQ//RT, QR//Su,

A.

134o

B.

132o

C.

96o

D.

48o

Correct answer is B

In the diagram; a = b = 48o (alternate < S)

x = 180o - b (angles on a str. line)

x = 180o - 48o

= 132o