The perimeter of rectangle abcd is 42 cm and the area is 80 cm2. which equation can be used to find the dimensions of the rectangle? (hint: set up a system of equations). xy + 2x + 2y = (42)(80) x^2 + 80x - 42 = 0 x^2 - 42x + 80 = 0 x^2 - 21x + 80 = 0

Don't hold me accountable but I believe it is the 2nd equation.

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

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8