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Help what is the length of side ?

Triangle area calculation formula 1. The known triangle bottom is a and the height is h, then S=ah/2. 2. If the two sides of the triangle are known to be a, b, and the angle of the two sides is C, then the product of the triangle with two sides multiplied by the sinusoidal value of the angle, that is, S=(absinC)/2. 3. Let the triangle trilaterals be a, b, c, and the radius of the inner tangent circle is r, then the triangle area S=(a+b+c)r/2.