Like the basic concept of inverse functions, the trigonometric inverse function has the same concept related to sine, cosine, tangent, cot, sec, and cosec. As addition is the inverse of subtraction and multiplication is the inverse of division, in the same way, trigonometry inverse functions work opposite to their value. For instance:
Sin-1(inverse sine) is the opposite of sine
Cos-1 (inverse cosine) is the opposite of cosine
Tan-1 (inverse tangent) is the inverse of a tangent
Cot-1 (inverse cotangent) works opposite to cot
Determining the value of the angle is possible with the inverse trigonometry function.
Mathematical Expression of Trig Inverse
Expressing statements mathematically,
Sinθ = Y has the inverse function as sin-1Y = θ.
Similarly,
It works the same for other functions of trigonometry. (-1) is not the exponent here. It simply represents the inverse function. Hence, it does not mean that Sin-1θ is equal to
1 / Sinθ. Inverse functions in trigonometry have the pretext in their name as –
Arcsine
Arccosine
Arctangent
Arccotangent
Arcsecant
Arccosecant
List of Trigonometry Inverse Functions Formulas Set
Formulas of inverse trigonometric functions discussed below have been grouped to convert one function to another, perform various operations, and determine the principal values of the angles. Besides, formulas of inverse trigonometric functions have been obtained from the basic trig functions formulas. It is classified into the following four sets –
Arbitrary values
Double and triple of functions
Complementary and reciprocal
Arithmetic operations of functions
Understanding Trigonometric Inverse Functions for Arbitrary Values
The negative values of inverse functions of sine, cosine, and tangent are transformed into the entire operations’ negative. The negatives of the importance of inverse functions of cosec, sec, and cot result in subtracting the function from the π.
Inverse Trig For Arbitrary Values | Result | Range |
Sin-1(-x) | -Sin-1x | X ∈ [-1, 1] |
Cos-1(-x) | – cos-1x | X ∈ [-1, 1] |
Tan-1(-x) | -tan-1x | X ∈ R |
Cot-1(-x) | – Cot-1x | X ∈ R |
Sec-1(-x) | – Sec-1x | X ∈ R – (-1, 1) |
Cosec-1(-x) | -cosec-1x | X ∈ R – (-1, 1) |
Double And Triple of Trigonometric Inverse Function Formulas
Both double and triple of the inverse trig functions are solved to get the single trigonometric function. For detailed information, the below table will be useful.
Double Of Inverse Function | Single Function Result | Triple Of Inverse Function | Single Function Result |
2 sin-1x | sin-1(2x.√(1 – x2)) | 3 sin-1x | sin-1(3x – 4x3) |
2 cos-1x | cos-1(2x2 – 1) | 3 cos-1x | cos-1(4x3 – 3x) |
2 tan-1x | tan-1(2x / 1 – x2) | 3 tan-1x | tan-1(3x – x3/1 – 3x2) |
Reciprocals and Complementary Functions
Inverse trigonometry functions for reciprocal values of x transform the given inverse trig function into a reciprocal function. Reciprocal in trigonometry point of view is as –
Sine is the reciprocal of cosecant and vice versa
Cosine is the reciprocal of secant and vice versa
Tangent is the reciprocal of cotangent and vice versa
On the other hand, the complementary function is the sum of two functions giving 90 degrees. In terms of trigonometry, the sum of the complementary inverse functions gives the right angle (90 degrees or π/2), as a result. Therefore, the sum of complementary functions such as tangent and cotangent, sine and cosine, secant and cosecant results in π/2.
Trigonometric Inverse Functions | Reciprocal | Range | Complementary Function | Sum Of Complementary Functions |
sin-1x | cosec-1(1/x) | X ∈ R – (-1, 1) | cos-1x | Sin-1x + cos-1x = π/2 |
cos-1x | Sec-1(1/x) | X ∈ R – (-1, 1) | Sin-1x | Sin-1x + cos-1x = π/2 |
Tan-1x | cot-1(1/x) -π + cot-1x | X > 0 X < 0 | Cot-1x | Tan-1x + cot-1x = π/2 |
Differentiation of Inverse Trigonometric Functions with The Domain and Range
Finding the differentiation of different inverse trig functions is evaluated using some formulas. Besides, the domain and range of trigonometric functions are decided based on graphs of sine inverse, cosine inverse, tangent inverse, cotangent inverse, cosecant inverse, and secant inverse.
Trigonometric Inverse Functions | Differentiation Formulas | Domain | Range |
Y = sin-1x, x ≠ -1, +1 | 1 / √(1 – x2) | [-1, 1] | [-π/2, π/2] |
Y = cos-1x, x ≠ -1, +1 | -1 / √(1 – x2) | [-1, 1] | [0, π] |
Y = tan-1x, x ≠ -i, +i | 1 / (1 + x2) | R | (-π/2, π/2) |
Y = cot-1x, x ≠ -i, +i | -1 / (1 + x2) | R | (0, π) |
Y = sec1x, |x| > 1 | 1 / [|x| √(x2-1] | (-∞, -1] U [1, ∞) | [0, π/2) U (π/2, π] |
Y = cosec1x, |x| > 1 | -1 / [|x| √(x2-1] | (-∞, -1] U [1, ∞) | [- π/2, 0) U (0, π/2] |
Conclusion
It is necessary to memorise the inverse trigonometric functions with their domain and range to solve and evaluate the inverse functions. The concept of reciprocals, double and triple, as well as other arithmetic operations of inverse trigonometric functions, is discussed in brief. We have also mentioned the differentiation formulas for every inverse trigonometry function to ensure easy and quick calculation.
Candidates preparing for entrance exams can check and go through the explanation of inverse trigonometric functions. In simple words, inverse trigonometric functions are the inverse or opposite of the basic functions in trigonometry.