AB is a chord of a circle at a distance 5 cm from the centre. If the length of the chord is 24 cm then the radius is ?
Answers
Answer:
13 cm
Step-by-step explanation:
Draw a perpendicular from center O on the chord. Suppose that perpendicular intersects AB( chord ) at C.
Then, join the center and A, again with another line join center and B.
Now, two triangles are formed.
In ∆AOC and ∆BOC,
• AO = BO ( radius )
• OC = OC ( common )
• /_ OCA = /_ OCB = 90°
Hence both the triangles are congruent.
Now it can be said AC = BC
It means that perpendicular divides the chord in two equal parts.
Length of each part = 1/2 of chord = 1/2 of 24 cm = 12 cm
So, AC = 12 cm
Distance between center and chord = OC = 5 cm
In ∆AOC, OC is at 90°, so we can use Pythagoras theorem,
= > radius² = AC² + OC²
= > AO² = 12² + 5²
= > radius² = 144 + 25 = 169
= > radius = √169 = 13
Radius of circle is 13 cm
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