Given: tangent to Circle O.

If m = 150Á, then A =

75

105

150

The degree measure of an arc is equal to the measure of central angle that intercept the arc.

m (arc DB) = 150°

m ∠ B O D = 150°

∠ A is inscribed angle, which is supplement of the 1/2 of the central angle (A is in the minor arc):

m∠ A = 180° - (150°/2) = 180° - 75° = 105°

Answer:

B) 105°