ACT Preparation / Unit 14 ACT 1318 short lesson, about 20 seconds
Sine, Cosine and Tangent
Captions available
The idea
For an acute angle in a right triangle, sine is opposite over hypotenuse, cosine is adjacent over hypotenuse, and tangent is opposite over adjacent: SOH-CAH-TOA.
In practice
In a 3-4-5 triangle, the angle opposite 3 has sine 3/5, cosine 4/5 and tangent 3/4.
Where people slip
The ratios depend only on the angle, not the triangle's size, which is why a calculator can give them.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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