Question

Help me with these questions ​

Answer 1

Answer:

1. b²-4ac=0

2. 8 cm

Step-by-step explanation:

Solution 1.

For a quadratic equation ax² +bx+c=0, b²-4ac is its discriminant (denoted with D).

If value of D(b²-4ac) is equal to zero,

then the roots of a quadratic equation are equal and real.

Solution 2.

Take a circle with centre O.

Draw a chord AB and draw OC perpendicular

to chord AB.

Length of chord AB = 12 cm

Radius of circle OB = 10 cm

BC = AB/2 = (12/2) cm = 6 cm

Distance between centre of circle O and

chord AB = OC

Applying Pythagoras theorem in right angled

triangle,

OB² = OC² + BC²

→OC² = OB² - BC²

→OC² = (10)² - (6)² cm = (100 - 36)cm = 64 cm

→OC =√64 = √8×8 cm

→OC = 8 cm (Ans.)