<Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (November 2013) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (November 2013) </Td> </Tr> <P> Angles between adjacent sides of a triangle are referred to as interior angles in Euclidean and other geometries . Exterior angles can be also defined, and the Euclidean triangle postulate can be formulated as the exterior angle theorem . One can also consider the sum of all three exterior angles, that equals to 360 ° in the Euclidean case (as for any convex polygon), is less than 360 ° in the spherical case, and is greater than 360 ° in the hyperbolic case . </P> <P> In the differential geometry of surfaces, the question of a triangle's angular defect is understood as a special case of the Gauss - Bonnet theorem where the curvature of a closed curve is not a function, but a measure with the support in exactly three points--vertices of a triangle . </P>

Who discovered how many degrees in a triangle