A roller coaster begins at 90 feet above ground level. Then it descends 105 feet. Find the height of the coaster after the first descent

In the diagram of circle o, what is the measure of zabc?

Solve the triangle. a = 21°, c = 105°, c = 5

Given: ae ≅ ce ; de ≅ be prove: abcd is a parallelogram. we have that ab || dc. by a similar argument used to prove that △aeb ≅ △ced, we can show that △ ≅ △ceb by. so, ∠cad ≅ ∠ by cpctc. therefore, ad || bc by the converse of the theorem. since both pair of opposite sides are parallel, quadrilateral abcd is a parallelogram.