In the trapezoid ABCD AD = 4, BC = 1, and its area is 35. Find the area of the triangle ABC.

Let us construct the height BH of the trapezoid and determine its length through the formula for the area of the trapezoid.

Savsd = (BC + AD) * BH / 2.

BH = 2 * Savs / (BC + AD) = 2 * 35/5 = 14 cm.

Let’s build the height AK of the triangle ABC. Since BH and AK are perpendicular to the bases AD and BC, then AKBN is a rectangle, and AK = BH = 14 cm.

Then Savs = BC * AK / 2 = 1 * 14/2 = 7 cm2.

Answer: The area of triangle ABC is 7 cm2.



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