WAEC Mathematics Past Questions & Answers - Page 177

881.

which of the following statements describes the locus of a point R which moves in a plane such that its equidistant from two intersecting lines?

A.

the bisector of the angle formed by the lines

B.

the point of intersection of the two lines

C.

A cone, with two intersecting lines as slant height

D.

A circle, with the point of intersection of the two lines as the center

Correct answer is A

No explanation has been provided for this answer.

882.

An arc of a circle of radius 14cm subtends angle 300o at the center. Find the perimeter of the sector formed by the arc

A.

14.67cm

B.

42.67cm

C.

101.33cm

D.

543.33cm

Correct answer is C

The perimeter of the sector \(=2r+\frac{\theta}{360}\times 2\pi r \\
\Rightarrow 28 + \frac{300}{360} \times \frac{2}{1} \times \frac{22}{7}\times \frac{14}{1} = \frac{220}{3}+28\\
73.133+28=101.33cm\)

883.

What is the total surface area of a closed cylinder of height 10cm and diameter 7cm? [Take \(\pi = \frac{22}{7}\)]

A.

77cm2

B.

227cm2

C.

297cm2

D.

374cm2

Correct answer is C

T.S.A of s closed cylinder = \(2\pi r(r+h)\\
=\frac{2}{1}\times \frac{22}{7} \times \frac{7}{2}\left(\frac{7}{2}+\frac{10}{1}\right)=\frac{22}{1}\left(\frac{27}{2}\right)=27\times 11=297cm^2\)

884.

Find the mean of the numbers 1, 3, 4, 8, 8, 4 and 7

A.

4

B.

5

C.

6

D.

7

Correct answer is B

mean \(=\frac{1+3+4+8+8+4+7}{7}=\frac{35}{7}=5\)

885.

Given that the root of an the equation \(2x^2 + (k+2)x+k=0\) is 2, find the value of k

A.

-4

B.

-2

C.

-1

D.

\(-\frac{1}{4}\)

Correct answer is A

Substituting for x in the equation
\(2(2)^2 + (k+2)2+k = 0 \Rightarrow 8 +2k + 4 + k =0 \Rightarrow 3k =-12; k=-4\)