In circle A shown below, Segment BD is a diameter and the measure of Arc CB is 36°: Points B, C, D lie on Circle A; line segment BD is the diameter of circle A; measure of arc CB is 36 degrees. What is the measure of ∠DBC?

Respuesta :

Answer:

The measure of ∠DBC is 72°.

Step-by-step explanation:

Given information: BD is a diameter, A is center of circle, Arc CB=36°.

According the angled inscribed in a semicircle theorem, the angle inscribed in a semicircle is a right angle.

[tex]\angle BCD=90^{\circ}[/tex]

According to the central angle theorem, the angle inscribed on the circle is half of its central angle.

[tex]\angle BDC=\frac{\angle BAC}{2}=\frac{36^{\circ}}{2}=18^{\circ}[/tex]

By angle sum property, the sum of interior angles of a triangle is 180 degrees.

[tex]\angle BDC+\angle BCD+\angle DBC=180[/tex]

[tex]18^{\circ}+90^{\circ}+\angle CBD=180^{\circ}[/tex]

[tex]108^{\circ}+\angle CBD=180^{\circ}[/tex]

[tex]\angle CBD=180^{\circ}-108^{\circ}[/tex]

[tex]\angle CBD=72^{\circ}[/tex]

Therefore the measure of ∠DBC is 72°.

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