which undefined geometric item can be described as a one dimensional set of points that has no beginning or end

Need on this geometry question. explain how you did it.

Icould really use some with this question.

Si la base de un triángulo isósceles mide 70 m y el ángulo opuesto a ésta mide 58°; entonces ¿cuánto mide la altura de dicho triángulo? a) 21.87 m. b) 40.01 m. c) 43.74 m. d) 63.14 m.