Q10 of 42 Page 202

Draw a line segment of length 7.2 cm and divide it in the ratio 5 : 3. Measure the two parts.

Need to draw a line segment with length 7.2cm


Also, to divide it 5:3 parts. Measure them.


⇒ Let m = 5 and n = 3


Construction steps:


1) Draw a ray AX, making an acute angle with AB.


2) Locate 8 = m + n points A1,A2,A3,A4,A5,A6,A7,A8 on AX such that AA1 = A1A2 = A2A3 = A3A4 = A4A5 = A5A6 = A6A7 = A7A8


3) Join BA8


4) Through the point A5 (m = 5) draw a line parallel to A8B at A5 intersecting AB at the point C. Then AC:CB = 5:3



⇒ Let the ratio be 5x:3x


⇒ 5x + 3X = 7.2cm


⇒ 8x = 7.2cm.


⇒ x =


⇒ x = 0.9cm.


Substituting ‘x’ value in 5x,3x we get


⇒ 5x = 5 × 0.9


= 4.5cm


⇒ 3x = 3 × 0.9


= 2.7cm.


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