Question

7(a). Copy and complete the table of values for the relation y=2sinx+1 for x=0° to 270° in steps of 30°.
7(b). Using scales of 2cm to 30° on the x-axis and 2cm to 1 unit on the y-axis, draw the graph of y=2sinx+1 for 0°≤x≤270°.
7(c). Use the graph to find the values of x for which sinx=1/4.

Accepted Answer

(a) Computed table: x: 0°,30°,60°,90°,120°,150°,180°,210°,240°,270°
y: 1.0, 2.0, 2.7, 3.0, 2.7, 2.0, 1.0, 0.0, −0.7, −1.0
(b) Plot these points on the given scale and draw a smooth sine curve through them.
(c) sinx=1/4 corresponds to y=2(1/4)+1=1.5. Reading from the graph where the curve crosses y=1.5 gives x≈14.5° and x≈165.5°.

WAEC Mathematics 2014 Theory — Question 12

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