The diagonal AC of a rectangular trapezoid ABCD is perpendicular to the lateral side of CD
The diagonal AC of a rectangular trapezoid ABCD is perpendicular to the lateral side of CD and makes an angle of 60 ° with the base of AD. Find the area of the trapezoid if AD = 24cm.
Since the AC is perpendicular to the СD, the ACD triangle is rectangular, in which the ADC angle = 180 – 90 – 60 = 30. Then the AC leg lies opposite the angle 30 and is equal to half the length of the BP diagonal.
AC = AD / 2 = 24/2 = 12 cm.
In a right-angled triangle ABC, the angle BAC = BAD – CAD = 90 – 60 = 30. Then the leg BC lies opposite the angle 30 and is equal to half the length of the hypotenuse AC. BC = AC / 2 = 12/2 = 6 cm.
In a right-angled triangle ACН, the leg CH = AC * SinСAН = 12 * √3 / 2 = 6 * √3 cm.
Determine the area of the trapezoid.
Savsd = (ВС + АD) * СН / 2 = (6 + 24) * 6 * √3 / 2 = 90 * √3 cm2.
Answer: The area of the trapezoid is 90 * √3 cm2.