Pythagoras' Theorem
Determining if a triangle is right-angled

Trigonometry

Pythagoras' theorem {Review}

• What is Pythagoras' theorem
• Finding the length of unknown sides
• Determining if a triangle is right-angled

Right-angled trigonometry​

• Finding unknown sides
• Finding unknown angles

Problem solving

• Angles of elevation and depression
• 3-Dimensional problems

Non-right-angled trigonometry

• Area of triangles
• Area of triangles proof
• Sine rule {Finding Unknown Sides}
• Sine rule {Finding Unknown Angles}
• ​Cosine rule​​

If the three side lengths of a triangle is known, Pythagoras' theorem can be used to determine whether or not that triangle is right-angled. This can be achieved by substituting the three sides into the formula to see if the equation balances.