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Two circles with radii 25 cm and 9 cm touch each other externally. The length of the direct common tangent is
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- 34 cm
- 30 cm
- 36 cm
- 32 cm
- 34 cm
Correct Option: B
On the basis of question we draw a figure of two circles with radii 25 cm and 9 cm touch each other externally.
Here , r1 = 25 cm, r2 = 9 cm
We find the required answer with the help of given formula ,
Length of common tangent = √(distance between centres)² - (r1 - r2)²
Length of common tangent = √(25 + 9)² - (25 - 9)²
Length of common tangent = √(34)² - (16)²
Length of common tangent = √(34 + 16)(34 - 16)
Length of common tangent = √50 × 18 = 30 cm.
