Introduction to basic trigonometry

• Identify the sides of right-angled triangles

• Calculate complementary angle of right-angled triangles

• The Hypotenuse

• The opposite side

• The adjacent side

• The three angles in any triangle add to 180°.

• Since one angle in a right-angled triangle measures 90°, the other two angles must add to 90° to make up the 180°.

• The two acute angles in any right-angled triangle are complementary angles (ie add to 90°).

• Use the two CAPITAL letters at its ends.

• Use one lower case letter which matches the opposite vertex (corner).

• Side GH can be called f.

• Identify the sides or angles

• Choose the right trig ratio based on what was given.

• Solve the equation to find the unknown

Remember, each of these ratios relies on you identifying the sides of the triangle based on your reference angle.

• Identify which 2 sides are "given"

• Which trig ratio goes with those sides?

• Set up a proportion

• Solve your proportion