Given:
Triangles FRI and DAY are similar.
To find:
Similarity ratio
Solution:
<em>If two triangles are similar then the corresponding angles are congruent and the corresponding sides are in proportion.</em>
Here, FR and DA are corresponding sides.

Cancel the common factors of 4 and 6, we get

⇒ FR : DA = 2 : 3
⇒ ΔFRI : ΔDAY = 2 : 3
Similarity ratio of the first triangle to the second triangle is 2 : 3.
Consider the absolute value, because we only worry about the quadrant later.


Thus, we know that the hypotenuse has a length of 4 units, and the side opposite the angle, A is √3, because this is the nature of the sine function in relation to its triangular component.
The missing side can be found using Pythagoras' Theorem:
4² - (√3)² = x²
16 - 3 = x²
13 = x²
x = √13

Since angle A is in the third quadrant, the tangent function will produce a positive angle.

