The internal angle of this figure is 90 degrees.

Anyway, we have no choice but to accept his proposal.

When light hits a mirror, the angle of incidence and the angle of reflection become equal.

The angle of friction of this material is 30 degrees.

It's difficult to solve this hexagonal puzzle.

Mr. Rokkaku is my best friend.

When light enters water, the angle of refraction changes.

The pheasant-tailed jacana, known as 'the ballerina of the water' for its beautiful appearance.

The calculation of the spherical angle is a part of geometry.

He was playing the guitar at the street corner.