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Inverse Trigonometry
⚫Introduction⚪ The inverse of a function f: A → B exists if f is one -one onto i.e. a bijection and is given by f(x) = y ⇒ f-1(y) =x.
⚪ Consider the sine function with domain R and range [-1,1]. Clearly this function is not a bijection and so it is not invertible. If we restrict the domain of it in such a way that it becomes one-one , then it would become invertible. If we consider sine as a function with domain [-π/2, π/2 ] and co-domain [-1,1] , then it is a bijection and therefore , invertible. The inverse of sine function is defined as sin-1x = θ where θ → [-π/2, π/2 ] and x → [-1,1]
⚫ Domain and range of trigonometry function
⚫ Basic Formula of Inverse Trigonometry :
sin-1(-x) = -sin-1x
cos-1(-x) = π -cos-1x
tan-1(-x) = -tan-1x
cot-1(-x) = π -cot-1x
sec-1(-x) = π -sec-1x
cosec-1(-x) = -cosec-1x
sin-1x + cos-1x = π/2
tan-1x + cot-1x = π/2
sec-1x + cosec-1x = π/2
Practice set 1 Practice set 2 Practice set 3
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