Question

plz answer 11th and 13th questions ....on the paper plz ....its urgent ....tomorrow i have pt2 exam ...so plz help me .wrong answer will be reported ...

Answer 1

Let fourth vertex be (x,y)

As mid point would be same

(2+0)/2 ,(1+1)/2= (3+x)/2,(4+y)/2

1,1= 3+x)/2 ,(4+y)/2

3+ x= 2

X= -1

4+ y= 2

Y= -2

13) 21, 18,15,.......0

First term = 21

Common difference= -3

0 = 21 + (n-1) ×-3

21= 3n -3

24= 3n

n= 8

Answer 2

Q.13=>the 8 term of an ap is 0
a=21
d=-3
an =0
an=a+(n-1)d
0=21+(n-1)(-3)
n-1=7
n=8