# Activities- Quadratic equations problems

From Karnataka Open Educational Resources

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# Ex.no.9.11 /problem no.9

The altitude of a triangle is 6cm greter than its base. If its area is 108cmsq .Find its base.

Statement: Solving problem based on quadratic equations.

- Interpretation of the problem:

* Converting data in to eqn.

*Knowledge about area of a triangle.

*knowledge of the formula of area of triangle.

*Methods of finding the roots of the eqn.

*Methods of finding the roots of the - Different approches to solve the problem:

*Factorisation - Using formula
- using graph
- Concept used:Forming the eqn. 216=x(x+6)

216=x2+6x

x2 +6x -216=0

Substitution: x 2 +18x-12x -216=0

Simplification: x(x+18)-12(x+18)=0

(x+18)( x-12)=0

(x+18)=0 (x-12)=0

x=-18, x=12

.

- Base=12cm,

Altitude=x+6

=12+6=18cm.

**Prior Knowledge** -

- Methods of solving the Eqn
- Factorisation
- Using Formula
- Using Graph