Derive the quadratic formula from the standard form (ax² + bx + c = 0) of a quadratic equation by
following the steps below.
1. divide all terms in the equation by a.
2. subtract the constant (the term without an x) from both sides.
3. add a constant (in terms of a and b) that will complete the square.
4. take the square root of both sides of the equation.
5. solve for x.

1. Divide all terms by a:

2. Subtract the constant (which is c/a):

3. Complete the square, then add the constant to both sides:

(now add the constant in terms of a and b)

(now simplify the fractions on the right side)

(now just put the b^2 in front)

4. Square root both sides and simplify the right side:

(you can square root the bottom bit of the fraction fully)

5. Now just solve for x:

(now simplify)

(note: it should be a plus or minus sign infront of the squareroot, not just a plus sign -it's just that i can't write it in )

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If you have any questions, feel free to ask.

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐