The angle measurements in the diagram are represented by the following expressions.
\qquad \blueD{\angle A=8x -10^\circ}∠A=8x−10
∘
start color #11accd, angle, A, equals, 8, x, minus, 10, degrees, end color #11accd \qquad \green{\angle B=3x + 90^\circ}∠B=3x+90
∘
start color #28ae7b, angle, B, equals, 3, x, plus, 90, degrees, end color #28ae7b

Solve for xxx and then find the measure of \greenD{\angle B}∠Bstart color #1fab54, angle, B, end color #1fab54:

d. it is a convex pentagon because it has five sides and none of the sides would extend into the inside of the polygon.

step-by-step explanation:

you can use a^2+ b^2=c^2

step-by-step explanation:

rectangles are made up of 4 right angles, which means that a side and a base meet perpendicular to one another.   their slopes then have to reflect perpendicular slopes.   perpendicular slopes are opposite reciprocals of one another.   for example, if the slope of one line is +2/3, then the perpendicular slope to that would be -3/2.   so we look for that combination in our choices.

all of them satisfy that condition (so what's the question, i guess? )