Solving Right-Angled Triangles (Leaving Cert Mathematics): Flashcards

Using trig ratios to find unknown sides or angles

Two pieces of information

$\sin θ = \frac{\text{opposite}}{\text{hypotenuse}}$

$\cos θ = \frac{\text{adjacent}}{\text{hypotenuse}}$

$\tan θ = \frac{\text{opposite}}{\text{adjacent}}$

Sine = Opposite ÷ Hypotenuse

Cosine = Adjacent ÷ Hypotenuse

Tangent = Opposite ÷ Adjacent

Longest side, opposite the right angle

When you know two sides and want to find an angle

4 decimal places

Degree mode (not radians)

$\frac{\text{adjacent}}{\cos θ}$