If the circumference of trapezoid ABCD is 25cm, ab \ \ CD, de \ \ BC and intersects AB with E, what is the circumference of triangle ade Can you give me more details? Maybe there are other ways?
Because ab \ \ CD, de \ \ BC, BCDE is a parallelogram
So de = BC, be = CD
L (triangle ADE) = AD + de + AE = AD + AE + BC
L (ladder ABCD) = 25 = CD + BC + be + AE + ad
So l (triangle ADE) = 25-2cd
There must be a few conditions for this topic, which can only be regarded as this step
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