A circle is inscribed in an isosceles trapezoid ABCD with bases AB = 7 and CD = 5.
A circle is inscribed in an isosceles trapezoid ABCD with bases AB = 7 and CD = 5. From point C the height CH is drawn, and from point H the perpendicular HE to the side BC. Find CE.
Since the circle is inscribed in the trapezoid, the sums of the sides of the trapezoid are equal.
AB + CD = AD + BC.
12 = AD + BC, and since the trapezoid is isosceles, then AD= BC = 12/2 = 6 cm.
The height of the CH divides the base AB into two segments, the length of the smaller of which is equal to: BH = (AB – CD) / 2 = (7 – 5) / 2 = 1 cm.
The segment EH is the height of the right-angled triangle CBH, drawn to the hypotenuse, then:
ВН ^ 2 = BC * BE.
BE = BH ^ 2 / BC = 1/6 cm.
Then CE = BC – BE = 6 – 1/6 = 35/6 = 5 (5/6) cm.
Answer: The length of the CE segment is 5 (5/6) cm.