# Angles of Elevation and Depression (10)

## Solve right-angled triangle problems including those involving direction and angles of elevation and depression (ACMMG245)

LO: To solve right-angled triangle problems using angles of elevation and depression.

Know:

• the properties of right-angled triangles.
• the trigonometric ratios and how to use them in context.

Understand:

• That we can use angles of elevation and depression to solve right-angled triangle problems.

Do:

• I can solve right-angled triangle problems involving angles of elevation and depression.

# Properties of Right-Angled Triangles

### “Opposite” is the opposite to the angle. “Adjacent” is next to to the angle. “Hypotenuse” is the long side of the right-angled triangle. # Trigonometric Ratios ### tan angle = opposite side / adjacent side # Angles of Elevation and Depression ### Depression means to “move down”, think of being depressed. It means to be down on yourself. If you can remember back to the angles unit when we talked about angles in parallel lines, angles of depression and elevation create “alternate angles”. Which means that they are equivalent or equal. # Bearings and Direction  