1) to show-

i) tri. DNM is cong. to tri.CNM

ii) DM=CN

__ i)PROOF__

angDMN=90 -INCLUDED ANGLE

MN=MN(COMMON) -SIDE

DN=CN -SIDE

SO THIS IS PROOVEN BY SAS CONG.CRIT.

ii) DN=CN (CPCT)

2)to show tri.ABC is ios.

BAD = CAD(GIVEN)

AD IS COMMON

BDA=CDA=90(GIVEN)

TRI. ADB IS CNGR.T TO ADC BY ASA

ANG B= ANG (CPCT)

AND AB=AC (CPCT)

THE TRI.ABC IS ISOSCELES BECAUSE 2 SIDES AND OPPOSITE ANGLES TO THE EQUAL SIDES ARE EQUAL.

3) HERE THE ANS IS THAT-

TRI.ABD IS CONGR.T TO TRI.ACD BECAUSE ALL SIDES AND ALL ANGLES OF THE TWO GIVEN TRIANGLES COINSIDE ONE ANOTHER.

ANG.B=ANG.C - THEY ARE CORRESPONDING PARTS OF CONGR.T TRIANGLES(CPCT).

ucan proove it ur own by the given informations

hope it helps and pls select it as the best ans if u think so. thank u :-)