The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 6cm + 7cm + 8cm = 21cm

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 3 x 1) + (2 x 1 x 3) + (2 x 3 x 3)
sa = (6) + (6) + (18)
sa = 30

A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.

For parallel lines with a transversal, the following relationships apply:

• angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
• alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
• all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
• same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with b° = 143, the value of w° is 37.

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(4²) + 2π(4 x 1)
sa = 2π(16) + 2π(4)
sa = (2 x 16)π + (2 x 4)π
sa = 32π + 8π
sa = 40π