Question 809043
Right angled triangle question.
Divide diameter by 2 to obtain 
the radius.
18/2 = 9cm.
Base side of triangle = 9cm.
Hypotenuse of triangle =
slant height = 21cm
Vertical side = height
Hypotenuse^2 - Base side^2 = Height^2
21^2 - 9^2 = Height^2
Height^2 = 360
Height = {{{sqrt(360)}}}
Height = 18.97cm (Two decimal places)
Hope this helps.
:-)