Answer:
height = 7 cm
Step-by-step explanation:
The area (A) of a trapezium is calculated using the formula
A = [tex]\frac{1}{2}[/tex] h(a + b)
where h is the height and a, b the parallel bases
here a = 6, b = 12 and A = 63, hence
[tex]\frac{1}{2}[/tex] × h × (6 + 12) = 63
[tex]\frac{1}{2}[/tex] h × 18 = 63
9h = 63 ( divide both sides by 9 )
h = 7
