Question

How to do this sum from 9th grade

Answer 1

Step-by-step explanation:

GIVEN

AB PARALLEL CD

O IS MID POINT OF AD

PROOF

OA =OD (given)

COD=AOB(vertically opposite angle)

DCB=CBA,(alternate interior angle)

since triangleAOB CONGRUENT TRIANGLE DOC

OC=OB(CPCT)

HENCE O IS MID POINT OF BC

HENCE PROVED

HOPE THIS HELPS YOU

Answer 2

given = AB||CD

AO=OD

To prove = ∆AOB=∆DOC

O is the midpoint of BC

prove = AO =OD (GIVEN)

CD=AB(GIVEN)

angle COD = angle AOB ( VARTACALLY OPPOSET ANGLES)

ACCORDING TO SAS RULE ∆AOP=∆DOC

HENCE O IS THE MIDPOINT