Find the perimeter of an isosceles trapezoid ABCD if you know that the measure of the angle is A = 30
Find the perimeter of an isosceles trapezoid ABCD if you know that the measure of the angle is A = 30, the smaller base is 2√3 and the height is 1 cm.
Let’s draw two heights of the trapezoid. Let’s get a projection of the upper base to the lower one.
Let’s denote one of the smaller segments of the lower (larger) base as x. Then this base itself is equal to 2√3 + 2x or 2 (x + √3).
We have an acute angle of 30 degrees, which means that the height of the trapezoid is equal to half of its lateral side. Those. side a is 2 * 1 = 2.
By the Pythagorean theorem, we find the side of the trapezoid.
a = x ^ 2 + 1 ^ 2 = x ^ 2 + 1.
Substitute the found value a into the equality.
2 = x ^ 2 + 1.
x ^ 2 = 1.
x = | 1 |, taking into account the conditions of the problem, x = 1.
Then the larger base of the trapezoid is 2 (1 + √3) = 2 + 2√3.
P = 2 * 2 + 2 + 2√3 + 2√3 = 6 + 4√3.
Answer: P = 6 + 4√3.