m∠abd = m∠dbc
step-by-step explanation:
given : ab bisects ∠dbc
as we know that bisection means ab divides ∠dbc in two equal angles named as ∠dba and ∠abc
so, m∠abd = m∠dbc
because ab bisects ∠dbc.
hence , the first statement m∠abd = m∠dbc is true.