- cosθ. secθ =1
- tanθ. cotθ =1
- tanθ = cossinθθ
- cotθ = cossinθθ
- sin^2 θ + cos^2 θ =1
- 1 + tan^2 θ = sec^2 θ
- 1 + cot^2 θ = cosec^2 θ
All the trigonometric ratios can be taught by keeping the embossed diagram and the table
of values in front. Let the child understand specific values by referring to the diagram and
the table back and forth.
Trigonometric ratios for complementary angles
- sin(90o - θ) = cosθ
- cos(90o - θ) = sinθ
- tan (90o - θ) = cotθ
- cot (90o - θ) = tanθ
- sec (90o - θ) = cosecθ
- cosec (90o - θ) = secθ
These ideas may be taught using logic. In the triangle, the three angles together will be
equal to 180^0. Since a right angle triangle is used for defining sin, cos, tan, etc, in the
σ = (^) NΣx