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.

A diagonal matrix is a matrix in which all elements outside the main diagonal are zero.

The diagonal elements of this matrix are all 1.

She worships the Horned God.

Amphibole, a type of mineral, is mainly found in igneous rocks.