Question

The angular diameter of a planet measured from earth is \(90''\). If the diameter of the planet is \(x \times 10^4\) m, then its distance from the earth is

• A. \(3.6\times10^9\text{ m}\)
• B. \(7.2\times10^9\text{ m}\)
• C. \(3.6\times10^8\text{ m}\)
• D. \(7.2\times10^8\text{ m}\)
• E. \(1.8\times10^8\text{ m}\)

Hint:

For very small angles: \[ \theta(\text{in rad})=\frac{\text{diameter}}{\text{distance}} \] and \[ 1''=\frac{1}{206265}\text{ rad} \]

Answer 1

The Correct Option is B