Q23 of 52 Page 1

Draw a right triangle in which the sides (other than hypotenuse) are of lengths 8 cm and 6 cm. Then construct another triangle whose sides are 3/4 times the corresponding sides of the given triangle.

Given,


AB = 8 cm,


BC = 6 cm and


Ratio = 3/4 of corresponding sides


Steps for construction;


(i) Draw a line BC of 8 cm.


(ii) Taking point B as center draw an arc with any radius


(iii) With the same radius draw an arc on the previous arc and mark the point Q.


(iv) Now taking Q as center with the same radius draw an arc again on previous arc and mark the point R.


(v) By taking the distance between Q and R as radius draw an arc from the point Q and with the same radius draw an arc from R point.


(vi) Draw a line from the point where both the arc intersect each other.


(vii) An angle of 90° is formed.


(viii) Draw a ray BX at an acute angle from point B.


(ix) Plot 4 points on BX so that B1 = B2 = B3 = B4


(x) Join B4 to point B.


(xi) Draw a line from B4 to point C and it is parallel to B3.


(xii) B3 meets BC at C’.


(xiii) So, BC’ parallel to BC.


Justification:


….. (i)


In ∆ ABC and ∆A’BC’


ABC = ABC (Common angle)


BCA = BCA (Coresponding angle)


So,


∆ ABC similar to ∆A’BC’ by AA similarity


Therefore,


BC’/BC = B3/B4 = 3/4 ………. (ii)


On compairing (i) and (ii)


A’B/AB = BC’/BC = 3/4 (Hence Proved)


So, we get the desired ∆ A’BC’


And ratio is 3/4 times of corresponding sides.


∆A’BC’ is the required triangle.


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