Looking at his dumb-looking face, it was hard for me to hold back my laughter.

He had to confront his dark side.

He attended the party wearing a mask.

Mr. Menode is my neighbor.

He always does his best to maintain his face.

A positive number is a number greater than zero.

This problem requires the calculation of the tangent.

This 正數 is the same as what I learned in school.

Calculating the value of secant, one of the trigonometric functions, is difficult.

The calculation of versine is a part of trigonometry.