Activities- Quadratic equations problems

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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
.

  1. Base=12cm,
    Altitude=x+6

=12+6=18cm.
Prior Knowledge -

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