MAT & Trig
Unit 2 Recap thru 2.2
Mathematician:
Reciprocal Identities
DEAL WITH DIFFERENT RATIOS
(the angles are exactly the same)
sin  
O
H
cos  
A
H
tan  
O
A
are the flipped version (reciprocal) of
_____  
H
O
_____  
H
A
_____  
A
O
Cofunctions
DEAL WITH DIFFERENT ANGLES – Pairs must add up to 90°
(the ratios are exactly the same)
Cosine has a cofunction of _________________.
Ex: cos(20°) = ____________
Secant has a cofunction of _________________.
Ex: sec(50°) = ____________
Cotangent has a cofunction of _________________.
Ex: cot(15°) = ____________
NOTE: The only two trig functions that are connected as reciprocals and cofunctions are:
Using the chart below…….
1) Put a circle around two trig functions that are COFUNCTIONS.
2) Put a triangle around two trig functions that are RECIPROCALS.

sin 
cos 
tan 
30
1
2
3
2
1
1
45
60
1
2
3
2
2
1
2
3
1
3
cot 
3
1
1
3
sec 
csc 
2
2
3
2
2
COFUNCTION (Different angles, but same ratio.)
EX:
Sin(30°) =
1
2
, which means its cofunction is _____________
RECIPROCAL (Different ratio, but same angles.)
EX:
Sin(30°) =
1
2
, which means its reciprocal is _____________
2
2
3