Question

plese do it , this is trigonometri lesson, so you if you want to do it use trigonometri ok

Answer 1

please see the attachment ....the answer is 

h=2.94mm

Answer 2

Please see the diagram in the attachment.
Length of BC = Length of DO = square root (OB^2 - OC^2) = square root (45^2 - 16^2)
= 42.06 mm
h = AO - DO = 45 mm - 42.06 mm = 2.94 mm