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2020 WAEC Mathematics Theory (a) Copy and complete the table of values for the relation y = 3 sin...

Mathematics
WAEC 2020

(a) Copy and complete the table of values for the relation y = 3 sin 2x. 

x o\(^o\) 15\(^o\) 30\(^o\) 45\(^o\) 60\(^o\) 75\(^o\) 90\(^o\) 105\(^o\) 120\(^o\) 135\(^o\)

\(^o\)

y 0.0         1.5         -2.6

 

(b) Using a scale of 2 cm to 15° on the x-axis and 2cm to I unit on the y-axis, draw the graph of y = 3 sin 2x for 0° \(\geq\) x \(\geq\) 150°.

(c) Use the graph to find the truth set of;

(i) 3 sin 2x + 2 = 0;

(ii ) \(\frac{3}{2}\) sin 2x = 0.25. 

 

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Explanation
x o\(^o\) 15\(^o\) 30\(^o\) 45\(^o\) 60\(^o\) 75\(^o\) 90\(^o\) 105\(^o\) 120\(^o\) 135\(^o\)

\(^o\)

y 0.0 1.5 2.6 2.1 2.6 1.5 0 - 1.5 - 2.6 - 3 -2.6

 

y = 35m\(^2\)x

when x = 15\(^o\)

y = 3 sin = (15\(^o\)) 

y = sin 30\(^o\)

y = 3 x \(\frac{1}{2}\) = 1.5

 

When x = 30\(^o\)

y = 3 sin 2(30\(^o\))

y = 3 sin 60\(^o\) = 2.6

 

When x = 45\(^o\) 

y = 3sin45\(^o\) 

= 2.1

 

When x = 60\(^o\) 

y = 3 sin 2(60\(^o\)) 

= 2 sin 120\(^o\) 

= 2.6

 

When x = 75\(^o\)

y = 3 sin 2(75\(^o\)) 

= 3 sin 150\(^o\) 

= 1.5

 

When x = 90\(^o\) 

y = 3 sin 2(90\(^o\)) 

= 3 sin 180\(^o\)

= 0

 

When x = 105\(^o\) 

y = 3 sin 2(105\(^o\)) 

= sin 210\(^o\) 

= -1.5

 

When x = 120\(^o\) 

y = 3 sin 2(120\(^o\)) 

= 3 sin 240\(^o\)

= -2.6

 

When x = 135\(^o\)

y = 3 sin 2(135\(^o\))

y = 3 sin 270\(^o\)

y = -3

 

 

(b

Open photo

(c)(i) 113

(ii) 3\(^o\) and 82\(^o\)

 

 


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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709