Tan α= 21/20, α lies in quadrant III, and cos β = -5/13, β lies in quadrant II, Find sin ( α + β ) ?

(hurry! ) which expression is equivalent to the following complex fraction?

Abdul is making a map of his neighborhood he knows the following information: his home, the middle school, and high school are all on the same street. his home, the elementry school, and his friends house are on the same street. the angle between the elementary school, middle school, and his home is congruent to the angle between his friends house, the high school, and his home. what theorem can abdul use to determine the two triangles are similar? a- side side side similarity theoremb- angle angle similarity theoremc- corresponding parts of similar triangles are congruentd- pieces of right triangles similarity theorem

Which geometric principle is used to justify the construction below?