Question

please answer the question it is very important

Answer 1

19. given,ac=bc
so,add deducting bc from both ab and CD. we can prove that ab=CD.

21.in triangle abc,
angle a = 90
ab=ac
therefore, angle b=anglec(angles opposite to the equal sides are equal)
let b be x
so c also x
x+x+90=180(angle sum)
2x+90=180
2x=180-90=90
x=90/2=45
therefore, b=c=45