In trapezium ABCD AB and CD base, AB = BC = 8, angle C = angle D = 60 degrees. Find the area of the trapezoid.
February 14, 2021 | education
| We will construct the heights АН and ВК of the trapezoid.
Since the angles at the base of the СD are equal, the trapezoid of AВСD is isosceles, Then AD = AB = BC = 8 cm.
The triangles AНD and ВCК are rectangular in which the angles DAН = СВK = (90 – 60) = 30.
Then the segments DН = СK = BC / 2 = 8/2 = 4 cm.
Quadrangle AВKН is a rectangle, then НK = AB = 8 cm.
Then the length of the segment AC = DН + НK + СK = 4 + 8 + 4 = 16 cm.
In a right-angled triangle AВD, according to the Pythagorean theorem, AH^2 = AD^2 – DN^2 = 64 – 16 = 48.
AH = 4 * √3 cm.
Then Savsd = (AB + СD) * AН / 2 = (8 + 16) * 4 * √3 / 2 = 48 * √3 cm.
Answer: The area of the trapezoid is 48 * √3 cm.
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