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 ?

Trigonometry Facts: The Amazing Unit Circle

Trigonometric Ratios of Special Angles: 0, 30, 45, 60, 90 (video lessons, examples, solutions)

Sin 90 Degrees: Formula, Examples, Questions

Unit Circle Quick Lesson - Printable PDF Chart · Matter of Math

How to Calculate the Sides and Angles of Triangles Using Pythagoras' Theorem, Sine and Cosine Rule - Owlcation

Sin Degrees Calculator

3 Expert Tips for Using the Unit Circle

Law of sines - Wikipedia

Value of sin, cos, tan, cot at 0, 30, 45, 60, 90 - Trigonometry Table

Sine Graph Trigonometry

Use the circle unit to find sin 90 degrees

Why does sin 90 degrees equal 1? We know that formula for sin is perpendicular upon hypotenuse where hypotenuse is longest side? - EduRev Class 10 Question

Inclined Plane Zona Land Education