Ab = x + 15ad = 2x + 18bc = 3 - xcd = 3x + 25 quadrilateral abcd is a parallelogram if both pairs of opposite sides are congruent. prove that quadrilateral abcd is a parallelogram by finding the value of x. a) x = 3 b) x = -5 c) x = -11 d) x = 11/2

We have AB = CD and AD = BC;

Then, x + 15 = 3x + 25 and 2x + 18 = 3 - x;

15 - 25 = 3x - x and 2x + x = 3 - 18;

- 10 = 2x and 3x = - 15 ;

x = - 5 and x = - 5;

The correct answer is x = - 5;

B) x = - 5

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2

step-by-step explanation: