हिंदी

If in two circles, arcs of the same length subtend angles 60° and 75° at the centre, find the ratio of their radii.

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प्रश्न

If in two circles, arcs of the same length subtend angles 60° and 75° at the centre, find the ratio of their radii.

योग
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उत्तर

Let r1, r2 and 01, 02 be the radii and angles subtended at the centre of two circles, respectively.

Let its radius = r1

l = r1θ1

= r1 `pi/3`

∴ r1 = `(3l)/pi` …(i)

For the second circle,

Let radius = r2

Arc length = l

The angle made by the arc at the centre, θ2 = 75°

= `75 xx π/180` radians

= `(5π)/12` radians

r= `(12l)/(5π)`

On dividing equation (i) by equation (ii)

`r^1/r^2 = (3l)/π + (12l)/(5π)`

= `(3l)/πxx(5π)/(12l)` = 5 : 4.

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अध्याय 3: Trigonometric Functions - EXERCISE 3.1 [पृष्ठ ४९]

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एनसीईआरटी Mathematics [English] Class 11
अध्याय 3 Trigonometric Functions
EXERCISE 3.1 | Q 6. | पृष्ठ ४९

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