The base of a solid oblique pyramid is an equilateral triangle with a base edge length of 14 units. what is bc, the height of the pyramid?

The picture in the attached figure

we know that
The base of a solid oblique pyramid is an equilateral triangle with a base edge length of 14 units
so
AC=CD=AD=14 units

in the right triangle ABC
tan A=opposite side angle A/adjacent side angle A
opposite side angle A=BC
adjacent side angle A=AC
angle A=45 degrees
so
tan 45=BC/14------------> BC=14*tan 45-------> BC=14*1-----> BC=14 units

the answer is
the height of the pyramid is 14 units (BC)