Math: How to find h in the picture?

Refer to the diagram below.
Draw a line from center O to the perpendicular to the horizontal lines and cut the horizontal lines at A and B respectively.
According to Geometry theorem, B is the point of contact.

OB and OC are the radii of the semi-circle.
OB = OC = 60/2 cm = 30 cm

In ΔOAC:
sin∠OCA = OA/OC
sin35° = OA/(30 cm)
OA = 30 sin35° cm
OA = 17.2 cm

h = OB - OA = 30 - 17.2 = 12.8 (cm)

from the centre of the semi circle , draw the perpendicular to the horizontal line
h=30 - 30sin35 = ...calculator