This document contains 28 trigonometric identities that need to be demonstrated by Segundo Huaccha Alvarez. The identities involve trigonometric functions like sine, cosine, tangent, cotangent, secant, and cosecant. They relate combinations of these functions through equalities, such as "sen x sec x = tg x". Segundo Huaccha Alvarez is asked to prove each of these 28 identities.