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WAEC Mathematics Past Questions & Answers - Page 298

1,486.

The value of tan 315°

A.

1

B.

√2/2

C.

0

D.

-1

E.

-√2/2

Correct answer is D

tan 315° = - tan (360 - 315) = - tan 45 = -1

1,487.

If cos θ = 5/13, what is the value of tan θ for 0 < θ < 90° ?

A.

13

B.

5

C.

13/5

D.

12/5

E.

5/12

Correct answer is D

cosθ=513

In the right- angled triangle, with an angle θ, the adjacent side to θ = 5 and the hypotenuse = 13.

opp^2 = 169 - 25 = 144 \implies opp = \sqrt{144}

= 12.

\tan \theta = \frac{opp}{adj} = \frac{12}{5} 

1,488.

Sin 60° has the same value as
I. Sin 120°
II. cos 240°
III. -sin 150°
IV. cos 210°
V. sin 240°

A.

I only

B.

II only

C.

IV only

D.

III only

E.

IV and V only

Correct answer is A

In the second quadrant, \sin 120 = \sin (180 - 120)

= \sin 60

1,489.

In the diagram above, PQT is an isosceles triangle.|PQ| = |QT|, ∠SRQ = 75°, ∠QPT = 25° and PQR is straight line. Find ∠RST

A.

20o

B.

50o

C.

55o

D.

70o

E.

75o

Correct answer is C

< PTQ = 25° (base angles of an isos. triangle)

\therefore < PQT = 180° - (25° + 25°) = 130° (sum of angles in triangle PQT)

\therefore < RST = 130° - 75° = 55° (exterior angle = sum of 2 opp. interior angles)