Trigonometry Flashcards
1
Q
Small angle approximation: sinθ ≈
A
θ
2
Q
Small angle approximation: cosθ ≈
A
1- θ2/2
3
Q
Small angle approximation: tanθ ≈
A
θ
4
Q
tanθ =
A
sinθ / cosθ
5
Q
cosecθ =
A
1 / sinθ
6
Q
secθ =
A
1 / cosθ
7
Q
cotθ =
A
1/tanθ or cosθ/sinθ
8
Q
Relationship between sin and cos (co-functions)
A
sinθ = cos( 90 - θ )
cosθ = sin( 90 - θ )
9
Q
Pythagoras (sin and cos)
A
sin2θ + cos2θ = 1
10
Q
Pythagoras (tan and sec)
A
1 + tan2θ = sec2θ
11
Q
Pythagoras (cosec and cot)
A
1 + cot2θ = cosec2θ
12
Q
Sin(2θ) =
A
2sinθcosθ
13
Q
cos(2θ) - including sin and cos
A
cos2θ - sin2θ
14
Q
cos(2θ) - including cos
A
2cos2θ - 1
15
Q
cos(2θ) - including sin
A
1 - 2sin2θ
