Question

13 The centre of a circle is C (20. - 1,30 + 1) and it passes through the point A (-3,-1).
If a diameter of the circle is of length 20 units, find the value (s) of a..
1
Hint. CA = radius of circle = x 20 units = 10 units
2
(20.-1+3)2 + (30+1 + 1)2 = 10
(2(a + 1))2 + (30 + 2)2 = 100
4 (02 + 20 + 1) +902 + 120 + 4 - 100 = 0
= 1302 + 20a - 92 = 0 = (0-2) (130 +46) = 0.​

Answer 1

Step-by-step explanation:

Centre: C(2a−1,7)

Point: P(−3,−1)

Radius=

2

1

(20)=10

As circle passes through P, distance between p and centre is equal to radius.

=>(PC)

2

=(10)

2

=>(2a−1+3)

2

+(7+1)

2

=(10)

2

=>(a+1)

2

=

4

36

=>(a+1)

2

=9