Sine, Cosine and Tangent in a Right Triangle

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1. 1. The ratios0:00
   • ✓$\sin\theta = \dfrac{\text{opposite}}{\text{hypotenuse}}$
   • ✓$\cos\theta = \dfrac{\text{adjacent}}{\text{hypotenuse}}$
   • ✓$\tan\theta = \dfrac{\text{opposite}}{\text{adjacent}}$
2. 2. Missing side0:13

3. 3. All three ratios0:27
   1. $$\sin\theta = \frac{5}{13}$$
   2. $$\cos\theta = \frac{12}{13}$$
   3. $$\tan\theta = \frac{5}{12}$$
4. 4. Recap0:35
   • ✓Label sides relative to $\theta$.
   • ✓Use the Pythagorean theorem for a missing side.
   • ✓Check: $\tan\theta = \dfrac{\sin\theta}{\cos\theta}$.

Sine, cosine and tangent as side ratios.

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