Triangle BDC is an isosceles triangle. Triangle ACE is a right-angled triangle. Show that triangle ABC is an equilateral triangle.

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

Thanh and her crew are building a stage in the shape of a trapezoid for an upcoming festival. the lengths of the parallel sides of the trapezoid are 14 ft and 24 ft. the height of the trapezoid is 12 ft.what is the area of the stage? enter your answer in the box. ft²

Isaac wants the equation below to have no solution when the missing number is placed in the box. which number should he place in the box?