Given,
L is the centre of the circle, MN is the diameter,
M is the point of contact and MCL = 55°
To find, the measure of CLN
Here,
(I) LMC = 90° {Diameter drawn from the point of contact to a circle is perpendicular to the tangent of the circle}
(II) CLN = LMC + MCL {The exterior angle of a triangle is equal to the sum of the non-adjacent interior angles of the triangle}
or, CLN = 90° + 55°
=145°
The measure of CLN is 145°.