Introduction
As we continue to study right triangles, let us review our prior knowledge.
So far we know that the sum of all three angles in any triangle equals 180°.
We also know that given a right triangle, the sides have a relationship as stated in the Pythagorean Theorem a2+ b2 = c2.
Now we will begin a study of Trigonometry which relates an acute angle in a right triangle and the ratio of two of the sides. For our purposes, we will only trigonometry in relation to triangles. Go to GeoGebra: ACCESS - Trig Intro. In this activity you have two sliders: a purple slider for the angle A and a green slider for side AB.
- Note which slider changes the shape and size of the triangle.
- Then notice which slider changes only the size of the triangle thus forming similar triangles.
- Notice what happens to the trig ratio result when you move each slider.
Which slider results in similar triangles when you move the slider? What happens to the trig ratios results when you move this slider?
Following successful completion of this lesson, students will be able to...
- Find trig ratios using right triangles
- Explain and use the relationship between the sine and cosine of complementary angles.
Enduring Understandings
- There is a relationship between the measure of the angles of a triangle and the measure of the sides of a triangle.
The above objectives correspond with the Alabama Course of Study: Algebra II with Statistics standards: .