1. ABCD is a quadrilateral in which angle A = angle C and angle B = angle D Prove that, if the opposite angles of a quadrilateral are equal, then the quadrilateral is a
parallelogram.

Quadrilateral ABCD is a parallelogram, quadrilateral with opposite sides parallel

Step-by-step explanation:

Statement,                                       Reason

∠A = ∠C,                                          Given

∠B = ∠D,                                          Given

Therefore, we have

∠A + ∠B + ∠C + ∠D = 360°,            Sum of interior angles of a quadrilateral

2×∠A + 2×∠B = 360°,                         Substitution property of equality

∴ ∠A + ∠B = 360°/2 = 180°

∠A + ∠B, are supplementary  angles,   Angles that sum up to 180°

Similarly,

∠C + ∠D, are supplementary  angles,   Angles that sum up to 180°

Therefore, segment DA is parallel to segment BC, (Lines with supplementary angles on the same side of the transversal)

Similarly, given ∠A = ∠C and ∠B = ∠D, we have;

∠A + ∠D and ∠C + ∠B are supplementary  angles,   Angles that sum up to 180°

Therefore, segment AB is parallel to segment DC, (Lines with supplementary angles on the same side of the transversal)

Therefore;

Quadrilateral ABCD is a parallelogram, quadrilateral with parallel opposite sides.

you can't solve x because it is 2 linear equation and you only have one equation

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,