Page 5 - Trigonometry

Standard values of Trigonometric ratios

o
o
o
o
o
∠A 0 30 45 60 90
sin A 0 1/2 1/√2 √3/2 1
cos A 1 √3/2 1/√2 1/2 0
tan A 0 1/√3 1 √3 not defined

cosec A not defined 2 √2 2/√3 1

sec A 1 2/√3 √2 2 not defined
cot A not defined √3 1 1/√3 0

Trigonometric Ratios of angle

Complementary Trigonometric ratios
If θ is an oblique angle, its complementary angle is 90∘−θ.

The subsequent relations hold true for trigonometric ratios of
angle.

• sin (90 −θ) = cos θ
∘
• cos (90 −θ) = sin θ
∘
• tan (90 −θ) = cot θ
∘
• cot (90 −θ) = tan θ
∘
• cosec (90 −θ) = sec θ
∘
• sec (90 −θ) = cosec θ
∘

Trigonometric Identities

• sin2θ + cos2θ =1

• 1 + cot2θ = cosec2θ
• 1 + tan2θ = sec2θ