Practice!

Sample Problem

The figure is not drawn to scale.

ABC is a straight line. Find ∠DBE.

∠DBE = °.

Solution

∠DBC = 90°.

∠ABE = 50°.

ABC is a straight line. Their sum is 180°.

∠ABE + ∠EBD + ∠DBC = 180°.

∠EBD = 180° − ∠DBC − ∠ABE

= 180° − 90° − 50° = 40°.

∴∠DBE = 40°.