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Area of a Triangle
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Right triangle ratios

Name the sides from one angle

opposite, adjacent, hypotenuse
thetaadjacentoppositehypotenuseSOH CAH TOAsin = opposite / hypotenusecos = adjacent / hypotenusetan = opposite / adjacentchoose theta, then name the sides

Pick an angle first. The hypotenuse is across from the right angle, the opposite side is across from your chosen angle, and the adjacent side touches it.