What is the fancy name (symbol) for the ratio of c/d?

Hello i need some with trigonometric substitutions. [tex]\int\limits^a_b {x} \, dx[/tex]

Question b of 10which of the following describe an angle with a vertex at a? check all that applyo a. labcов. савd dooo c_baco d. zacb

In trapezoid abcd, ac is a diagonal and ∠abc≅∠acd. find ac if the lengths of the bases bc and ad are 12m and 27m respectively.