If you know the sum of the angles of any
triangle is 180^{o}, you do not need trigonometry functions
to calculate the size of an angle when the other two angles
are known. The following applet will help you visualize
an important triangle calculation tool:

The "Introduction" reviews the
Pythagorean theorem. "Naming Sides" reviews
the trigonometry triangle names required to use "Soh
Cah Toa". The "Practice" section has 5
sections of problem types. For this activity complete
problem types 10 - 12. The activity below this one focuses
on the same 3 problem types.

Problem Types 1-3: Pythagorean Theorem.

Problem Types 4-6: Calculate the sine, cosine and tangent
ratios given one reference angle.

Problem Types 7-9: Calculate the sine, cosine and tangent
ratios given two appropriate sides.

Problem Types 10-12: Calculate the reference
angle given two appropriate sides.

Problem Types 13-18: Calculate the length of one of
the sides given appropriate side and reference angle.

Using
Trigonometry to Calculate Angles

If we know the length of two sides of a right
triangle ABC we can calculate the size of either acute angle
using one of the trigonometry functions. The buttons
below show the sides and trigonometry function you will
need to calculate an angle. Click each "A"
button to learn how to calculate the angle using our 3 trigonometry
functions.