How do i find the sin 11pi/2 without using a calculator?

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Kayla wants to find the width, ab, of a river. she walks along the edge of the river 65 ft and marks point c. then she walks 25 ft further and marks point d. she turns 90° and walks until her location, point a, and point c are collinear. she marks point e at this location, as shown. (a) can kayla conclude that δ and δ are similar? why or why not? (b) suppose de = 15 ft. what can kayla conclude about the width of the river?

Aline passes through 3,7 and 6,9 what equation represents the line