A rectangular red sticker has an area of 18square millimeters and a perimeter of 18millimeters. What are the dimensions of the sticker?_____ millimeters by _____ millimeters
Q. A rectangular red sticker has an area of 18square millimeters and a perimeter of 18millimeters. What are the dimensions of the sticker?_____ millimeters by _____ millimeters
Define Variables: Let l be the length and w be the width of the rectangle.The area of a rectangle is given by the formula A=l×w.
Area and Perimeter Formulas: The area of the sticker is given as 18 square millimeters.Substitute 18 for A in the formula A=l×w.18=l×w
Substitute Values: The perimeter of a rectangle is given by the formula P=2l+2w.The perimeter of the sticker is given as 18 millimeters.Substitute 18 for P in the formula P=2l+2w.18=2l+2w
Simplify Perimeter Equation: Divide the perimeter equation by 2 to simplify.218=22l+2w9=l+w
Solve System of Equations: We now have two equations with two variables:18=l×w (Area equation)9=l+w (Perimeter equation)We can solve this system of equations to find the values of l and w.
Express Width in Terms of Length: From the perimeter equation, express w in terms of l.w=9−l
Substitute into Area Equation: Substitute w=9−l into the area equation.18=l×(9−l)
Expand and Rearrange Equation: Expand the area equation and move all terms to one side to form a quadratic equation.18=9l−l20=l2−9l+18
Factor Quadratic Equation: Factor the quadratic equation.0=(l−3)(l−6)
Solve for Length: Solve for l by setting each factor equal to zero.l−3=0 or l−6=0l=3 or l=6
Final Dimensions: If l=3, then w=9−l=9−3=6. If l=6, then w=9−l=9−6=3. So the dimensions of the sticker can be 3 millimeters by 6 millimeters or 6 millimeters by 3 millimeters (since a rectangle's length and width are interchangeable).
More problems from Area and perimeter: word problems