1. ## Finding the length

I have an issue with this question that why in the solution 2 is multiplied to the radius of 6400.

The question is....

Q)the angle subtended by the earth at the eye of the spaceman landed on the moon is 1 degree 54 minute.The radius of earth is 6400 km.Find the approx distance b/w the moon and the earth.

Solution:

r=L/Theta
r=2*6400/0.033155

r=386065.45 km Ans

2. Hi

Since L is much bigger than r, we have $\tan \frac{\theta}{2} \approx \frac{r}{L}$

Since the angle is very low, we have $\tan \frac{\theta}{2} \approx \frac{\theta}{2}$

Therefore $\frac{\theta}{2} \approx \frac{r}{L}$

3. cant understand u

4. Hello, haftakhan!

Did you make a sketch?

Q) The angle subtended by the earth at the eye of the spaceman
on the moon is 1 degree 54 minutes. The radius of earth is 6400 km.
Find the approx distance b/w the moon and the earth.
Code:
                                      *
*   *   | - *
*         *     |R    *
*                *      |      *
o        @               *      *      *
*                *      |      *
*         *     |R   *
*   *   |   *
*

Do you see why we use 2R ?