How is sine of 90 degree possible

I don't know how can a triangle be formed with two angles each 90 degree. If it is not possible, then how do we calculate sin 90 degree = 1 ?

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Use the circle unit to find sin 90 degrees

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Find the exact values of the following. cos 270 degrees = 90 degrees, value = 0. Sin 180 degrees =

sin 90 Degrees Equals 1 Why?

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