Which trigonometric function requires a domain restriction of [-pi/2, pi/2] to make it invertable?

Step-by-step explanation:

The trigonometric function that needs a domain restriction of to make it invertible is .

The function will pass the horizontal line test on this interval therefore making it an invertible function on this interval.

This explains why the inverse tangent function, has range .

step-by-step explanation:

y = | -2(-2) |     →     y = | 4 |     →     y = 4       ⇒   (-2, 4)

y = | -2(-1) |     →     y = | 2 |     →       y =   2       ⇒   (-1, 2)    

y = | -2(0) |     →     y = | 0 |     →       y = 0         ⇒   (0, 0)

y = | -2(1) |   c →     y = | -2 |     →     y =   2         ⇒   (1, 2)    

y = | -2(2) |     →     y = | - 4 |     →     y =   4         ⇒   (2, 4)  

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