Trigonometry - Related angles
Calculators are not allowed
Learners should have some knowledge of:
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The graphs of y  sin x , y  cos x and y  tan x
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How angles in quadrants 2, 3 & 4 can be related to angles in the 1st quadrant
Exact values for trig ratios
Radians (extension)
Give learners card set A
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Ask learners to group the cards in any way they see fit.
It is likely they will group them by trig function, although they may decide to group
them according to the size of the angles. Some might group the cards according to their
value, i.e. positive or negative.
Ask the learners to group the cards in another way.
Ask learners which is greater: sin 30 or tan 60 . How do they know?
Ask them which is greater: sin100 or tan 200 ? How do they know?
This is an opportunity to look at the graphs of the trig functions and perhaps use the
four-quadrant diagram.
Ask learners to group the cards into positive or negative values. (Any who did this
previously could attempt to arrange the cards in order of size.)
Ask learners if they know the values of any of the expressions. This is an opportunity to
recap the exact values.
Ask the learners to arrange the cards in order of size.
Give learners card set B and C
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Ask them to arrange the cards into groups of equal values
Extension working with radians
Give learners cards set D
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Ask them to match the cards form set D to the groups of cards created earlier.
Card Set A
A
A
sin30
A
cos45
A
tan60
A
sin120
A
cos150
A
tan135
A
sin210
A
cos240
A
sin315
tan300
Card Set B
B
B
B
tan60
B
sin45
cos60
B
sin30
tan45
B
cos30
B
B
sin60
B
tan240
B
cos315
sin150
Card Set C
C
C
1
0.5
C
C
C
C
1
2
C
0.5
C
3
3
2
 3
2
C
C
1
2
1
2
3
Card Set D
D
D
D
D
D
sin
6
tan
3
cos5
6
sin7
6
sin7
4
D
D
cos
4
sin 2
3
D
tan3
4
D
cos4
3
tan5
3
D