Unit 7 Right Angled Triangles

Right angled triangles have

  • one angle that measures 90 degrees;
  • a side called the hypotenuse which lies opposite the 90 degree angle;
  • two smaller angles that add together to 90 degrees

In a problem involving only the sides of the right angled triangle, we use Pythagoras’ Theorem to solve it.


In a problem involving an angle, we use trigonometry (the SOH CAH TOA formulae) to solve it.

    \[\sin \theta = \frac{\text{opp}}{\text{hyp}}\]

    \[\cos \theta = \frac{\text{adj}}{\text{hyp}}\]

    \[\tan \theta = \frac{\text{opp}}{\text{adj}}\]

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