Experts please help me to solve question no. 4

Join AC
in triangle ABC
<BAC > <BCA  because side opposite larger side is larger and here BC > AB # AB is the smallest side
in triangle ADC
<DAC > <DCA  because side opposite larger side is larger and here DC > AD # AD is the largest side
since
<BAC > <BCA and <DAC > <DCA 
<BAC  + <DAC > <BCA + <DCA 
< BAD > < BCD i.e. <A > < C

Similarly Join BD and in trianlges BAD and ACD
<ABD > <ADB since AB is the shortest side AD> AB and thus <ABD opp AD is >  <ADB opp AB
<CBD > <CDB since CD is the largest side  CD > BC and thus <CBD opp CD > <CDB opp BC
and
thus <ABD + <CBD > <ADB + <CDB
< ABC > < ADC
<B > <D