# Angle Addition Postulate

Activity

## Drag the points A, B, C and D in the sketch below

## Determine whether the following statement is always, sometimes, or never true.

D is in the interior of ∠ABC

## Determine whether the following statement is always, sometimes, or never

m∠ABD + m∠DBC = m∠ABC

## If D is in the interior of ∠ABC , m∠ABC=123° and m∠ABD=55°

m∠CBD=?

## If m∠ABD=130° and m∠ABC=50°

m∠DBC=?