As shown in the figure, the length of line segment AB is 20cm, C is the point on line segment AB, AC = three fourths AB, extend AB to D reversely, so that ad = one fourth AB, P is the midpoint of line segment CD, given AP = 15cm, calculate the length of line segment CD

This. It can be calculated without P point
First, ab = AC + BC
∵AC=3/4AB
So BC = 1 / 4AB
And ∵ ad = 1 / 4AB
So ad = AC
So AD + AC = AC + BC
∵AC+BC=AB=20cm
So AD + BC = AB = 20cm

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