Introduction to BASIC Trigonometric Functions
OPTION ANGLE DEGREES
When OPTION ANGLE DEGREES is written, the unit of angles is set to be degrees.
Example.

    10 OPTION ANGLE DEGREES
    20 PRINT SIN(30),COS(30),TAN(30)
    30 END

On this case, SIN(30),COS(30),TAN(30) stand for sin30°, cos30°, tan30°, respectively.

Inverse Cosine

The angle θ of which the cosine is x can be obtained by ACOS(x).

The range of ACOS(x) is from 0° to 180°.

Example. A program that finds the angle A from the length a, b, c of three sides of a triangle by applying the cosine law.

    10 OPTION ANGLE DEGREES
    20 INPUT a,b,c
    30 PRINT ACOS((b^2+c^2-a^2)/(2*b*c))
    40 END

Refer to Trigonometric Functions