Answer:
5√15cm or 19.36cm
Step-by-step explanation:
An isosceles triangle has two congruent sides.
The height of an isosceles triangle is also the median and the perpendicular bisector of the triangle dividing the base in half and forming two congruent right triangles.
a squared + b squared = c squared
5 squared + h squared = 20 squared
25 + h squared = 400
h squared = 375
h =√375
h = 5√15 cm
h = 19.36 cm