Geometrymedium · Past Paper
If two circles of radii 18 cm and 8 cm touch each other externally, find the length of their direct common tangent.
A10 cm
B24 cm
C26 cm
D14 cm
✓ Correct Answer: B — 24 cm
Length = sqrt(d^2 - (r1-r2)^2). d = 18+8=26. L = sqrt(26^2 - 10^2) = sqrt(676-100) = sqrt(576) = 24 cm.
Share this question
More from Geometry
- The perimeter of an equilateral triangle is 18 cm. Its area is:
- If a point P lies inside a circle, how many tangents can be drawn from P to the circle?
- Equation of a line making intercepts a and b on the x and y axes respectively is:
- Find the length of the arc of a circle of radius 7 cm which subtends an angle of 90 degrees at the center.
- The sum of the altitudes of a triangle is _____ its perimeter.