Question 274708
240/3=80' length of a side
The altitude divides the triangle into two 30-60-90 triangles. 30-60-90 triangles have a ratio of their sides of base 1, hypotenuse 2, altitude sqrt(3). Since either of the two triangles is similar it has: hypotenuse 80, base 40 and altitude 40sqrt(3). This type question is frequently on the SAT.
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Ed