Question
Thu March 07, 2013 By:
 

In Ex 11.2 Of This Chapter In Third question Why Did we Take 2cm Below the angle as in other questions we took the cms on the angles made??

Expert Reply
Thu March 07, 2013
In the third question, the difference between two sides of the triangle is given and when the difference is given, two cases arise. The two are given below:
 

   Eg: Construct a triangle with base of length 7.5 cm, the difference of the other two sides 2.5 cm, and one base angle of 45°

          Given          : In ΔABC, base BC = 7.5 cm, the difference of the other two sides, AB – AC or AC – AB = 2.5 cm and one base angle is 45°.

          Required      : To construct the ΔABC,

          CASE (i) AB – AC = 2.5 cm.

          Steps of Construction:

  1. Draw BC = 7.5 cm.
  2. At B, construct angleCBX = 45°.
  3. From BX, cut off BD = 2.5 cm.
  4. Join CD.
  5. Draw the perpendicular bisector RS of CD intersecting BX at a point A.
  6. Join AC. Then, ABC is the required triangle.
 

CASE (ii) AC – AB = 2.5 cm

Steps of Construction:

  1. Draw BC = 7.5 cm.
  2. At B, construct angleCBX = 45° and produce XB to form a line XBX’.
  3. From BX’, cut off BD’ = 2.5 cm.
  4. Join CD’.
  5. Draw perpendicular bisector RS of CD’ intersecting BX at a point A.
Join AC. Then, ABC is the required triangle.
 
 
To know more about contructions, you can go through the videos of this chapter available on our site.
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