Question

Two concentric circles are of radii 17 cm and 8 cm. Find the length of the chord of

the larger circlewhich touches the smaller circle.​

Answer 1

Step-by-step explanation:

its simple,

name the chord as abc or whatever you want

now ab=bc

and abc= ab+bc or 2ab (b is the midpoint of the chord which touches the smaller circle.)

Now you can say that bo is also perpendicular to abc

where o is the centre of both circle.

next you have a right angle ∆ oab

where oa²=ab²+ob²

(17cm)²=ab²+(8cm)² ...(oa is the radii of larger circle and ob radii of the smaller one)

ab²=( 17cm)²-(8cm)²

ab²= 289cm²-64cm²

ab=✓225cm²

= 15cm

and we know abc= 2 ab = 2×15cm= 30cm