Identites/formula Etc. Flashcards
Reciprocal identity of cosecx
1 / sinx
Reciprocal identity of secx
1 / cosx
Reciprocal identity of cotx
1 / tanx
Give a pythagorean identity with cos²x
Sin²x + Cos²x = 1
Give a pythagorean identity for sec²x
Sec²x = 1+tan²x
Give a pythagorean identity for cosec²x
Cosec²x = 1 + cot²x
Addition rule for sin(A±B)
SinAcosB ± cosAsinB
Addition rule for cos(A±B)
CosAcosB - or + sinAsinB
Addition rule for tan(A±B)
Tan(A±B) = tanA ± tanB / 1 - or + tanAtanB
Sin2A double angle formula
2sinAcosA
Cos2a double angle formula
Cos²A - sin²A
Or
2cos²A - 1
Or
1 - 2sin²A
Tan2a double angle formula
2tanA / 1 - tan²A
Equation for working out arc length of a sector
S = rtheta
Equation for workout out sector area
A = (1/2)r²(theta)
Give the small angle approximation for sin(theta)
Theta
Give the small angle approximation for cos(theta)
1 - (1/2)(theta)²
Give the small angle approximation for tan(theta)
Theta
Equation to work out the distance between 2 coords
D = root((2nd x - 1st x)² + (2nd y - 1st y)²)
Gradient between 2 coords
(2nd y - 1st y) / (2nd x - 1st x)
Cosine rule
a² = b² + c² -2bcCosA
You can use this rule when:
You know all 3 sides
You know 2 sides and the angle between them