Angles in a spherical triangle. Find the sum of the angles in the spherical triangle shown in Fig. 1.5, assuming A is at the pole and a = radius of sphere. In order to find the angle at A, consider what would be the value of a in order for the angle to be 900.
Figure 1.5
![2217_4d85fc4f-d328-4238-ad31-c9450243bd9a.png](https://secure.tutorsglobe.com/CMSImages/2217_4d85fc4f-d328-4238-ad31-c9450243bd9a.png)