Page 42 - modul trigonometri bilingual

Pythagoras identity

+ =
+ =

+ =
4. Trigonometric Identity Proof

The steps prove the identity of trigonometry.
a. Change all trigonometric functions to the basic functions of
sine and cosine.
b. Change it to the simplest form.

In simplifying, the following strategies can be used.
1) Equal the denominator.
2) Multiply a trigonometric form by another trigonometric

sin cos
form equivalent to 1, for example or .
sin cos
3) Add a trigonometric shape with another trigonometric
form equivalent to 0, for example (sin − sin ) or

(cos − cos ).

Trigonometric identity can be proven in one of the following ways.

1. If the shape of the left segment of the equation is more complex, change the shape of
the left segment of the equation so that it is exactly the same as the right segment
equation.
2. If the shape of the right field of the equation is more complex, change the shape of the
right segment to exactly the same as the left segment of the equation.
3. The left and right sections are changed to other shapes so that the final shapes of the
two segments are exactly the same.

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