Prove that AB is tangent to circle

See Explanation

Step-by-step explanation:

.....(1)

..... (2)

From equations (1) & (2)

Therefore, by converse of Pythagoras theorem, triangle ABO is right angled triangle right angle at B.

Therefore,

Radius OB is perpendicular to AB.

Hence, AB is tangent to the circle with center O at the points B.

the common difference is = 7

Step-by-step explanation:

1st term is 13

2nd term is 20

d = 2nd -1st

d= 20-13

d= 7