Question

If y = 3x + c is tangent to the circle x² + y2 = 10, then the value of c is​

Answer 1

differentiate both side of circle eqn

and solv line and circle equation

Answer 2

here ans: plus minis 10

Given, line is 

 3x-y+c=0

y= 3x+c

And equation of circle is x² + y² = 10

Here, a² = 10 , m = -3

If given line touches the circle, then

Length of intercept = 0

2 under root a²(1+m) - c²/ 1 + m² = 0

2 under root 10(1+9) - c²/ 1 + 9 = 0

under root 100 + c² = 0

under root 100 = c²

c = plus minus 10