Question

AB and CD are two parallel chords of a circle such that AB = 10 cm and CD = 24 cm. If the chords are of the opposite sides of the centre and distance between them is 17 cm, then the radius of the circle is

Answer 1

List some of the technological changes associated with this period. NCERT Class 7th Social Science (Our Pasts II) Chapter 1 Tracing Changes Through A Thousand Years

Use of Persian wheel in irrigation.

Spinning wheel in weaving.

Firearms in combats.

New food like potatoes,tea,coffee corn,chilies etc.

Answer 2

Given, MN = 17 cm

Let ON = x

Then, OM = 17 - x

△AOM,

OA2=OM2+AM2

=> r2=(17−x)2+52

= 289+x2−34x+25

r2=314+x2−34x ...(i)

OC2=ON2+CN2

=> r2=x2+122=x2+144 ...(ii)

From Eqs. (i) and (ii), we get

314+x2−34x=x2+144

=> 34x = 170

=> x = 5

From Eq. (ii), r2=25+144=169

r = 13 cm