The lenght of a rectangle is 3 inches more then its width. Its perimeter is 42 inches, find the dimensions of the rectangle

The problem uses the perimeter formula.  P = 2w + 2l   where w is the width, and l is the length.

We know the length (l) is 3 inches longer than it's width (or l = w+3).  Substitute w +3 into Perimeter equation.

P = 2w + 2(w+3).  That simplifies to P = 4w + 6.

Since P + 42,   we have 42 = 4w +6.  With some simple algebra we find that w = 9 and l = 12.

Shania is correct.

Step-by-step explanation:

For a right angled triangle, given two sides and an angle, we can use the sine rule or the various trigonometry identities to solve the triangle;

a/sin A = b/sinB

and

sin (angle) = opposite side/hypotenuse

cos (angle) = adjacent side/hypotenuse

tan (angle) = opposite/ adjacent

assuming a is the opposite side of angle A and b is also opposite of angle B

Otherwise, the only way to solve a triangle given two sides only is by the use of the Pythagoras theorem.

Hence, Shania is correct.