In circle A, Segment BD is a diameter, and the measure of arc CB is 36°:

Points B, C, and D lie on Circle A. Line segment BD is the diameter of circle A; the measure of arc CB is 36 degrees.

What is the measure of ∠DBC?

36°
72°
18°
54°

1 answer

To find the measure of \(\angle DBC\), we can use the relationship between angles and arcs in a circle.

Given that:

  • \(BD\) is the diameter of circle \(A\), it means that angle \(\angle BCD\) will be a right angle (90 degrees), because an angle inscribed in a semicircle is always a right angle.
  • The measure of arc \(CB\) is 36 degrees.

Using the fact that the measure of an angle inscribed in a circle is half the measure of the arc that it subtends, we have:

\[ \angle DBC = \frac{1}{2} \times \text{measure of arc CB} \]

Since the measure of arc \(CB\) is 36 degrees:

\[ \angle DBC = \frac{1}{2} \times 36 = 18 \text{ degrees} \]

Therefore, the measure of \(\angle DBC\) is \( \boxed{18^\circ} \).