Topic Quiz Q.4: Two-dimensional figures

Question 1 of 10 · Pythagorean theorem

No calculatorHot spot

This right triangle is drawn with its right angle at the top. Click the hypotenuse.

Click on the figure to mark your answer (or focus it and use the arrow keys).

Right triangle drawn with the right angle at the top vertex; the two slanted sides meet at the top, and the third side runs along the bottom
Hint

Find the small square that marks the right angle first. Which side does not touch that corner?

Question 2 of 10 · Triangles and rectangles: area and perimeter

A triangular piece of sheet metal is shown below. The dashed line shows the height.

Obtuse triangle with a base of 8 m. The base is extended with a dashed line, and a dashed height of 6 m drops from the top vertex to the extended base outside the triangle, meeting it at a right angle. The two slanted sides are 12.5 m and 6.7 m. 8 m 6 m 12.5 m 6.7 m

What is the area of the triangle?

Answer choices
Hint

The height does not have to be inside the triangle. Look for the segment that meets the (extended) base at a right angle.

Question 3 of 10 · Circles: area and circumference

A large pizza is 16 inches in diameter. To the nearest square inch, what is the area of the top of the pizza? Use \pi \approx 3.14.

Answer choices
Hint

Pizza sizes give the distance straight across. What does the area formula need?

Question 4 of 10 · Circles: area and circumference

Fill in

A round backyard trampoline has a diameter of 14 feet. What is the area of the jumping surface? Use \pi \approx 3.14.

ft²

Type your answer in the box. Fractions like 3/4 are fine.

Hint

The area formula uses the radius. What do you need to do with the diameter first?

Question 5 of 10 · Pythagorean theorem

Drop-down

A 15-foot ladder leans against a building and touches the wall 12 feet above the ground. Let x be the distance from the bottom of the ladder to the building.

The equation can be used to find x. The bottom of the ladder is feet from the building.

Choose an answer from each menu.

Hint

Which length is across from the right angle where the wall meets the ground? That one goes alone on one side of the equation.

Question 6 of 10 · Polygons: area and perimeter

The floor of a gazebo is a regular hexagon with sides of 6 feet. The apothem (the distance from the center to the middle of a side) is about 5.2 feet.

What is the approximate area of the floor?

Answer choices
Hint

Split the hexagon into triangles from its center. How many triangles, and what are each one's base and height?

Question 7 of 10 · Composite 2-D figures

Fill in

A concrete walkway 3 ft wide is built around all four sides of a rectangular pool that measures 20 ft by 10 ft, as shown.

Rectangular pool 20 ft by 10 ft surrounded by a shaded walkway 3 ft wide on every side pool 20 ft 10 ft 3 ft

What is the area of the walkway?

ft²

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Find the outside length and width of the pool plus the walkway. The walkway adds 3 ft on each side.

Question 8 of 10 · Composite 2-D figures

Fill in

A machine shop starts with a rectangular metal sheet. It cuts a right triangle from one corner and a square hole from the middle, as shown. The shaded part is the metal that is left.

Rectangular metal sheet 20 cm by 15 cm. A right triangle with legs 8 cm (along the bottom) and 6 cm (up the left side) is cut from the bottom-left corner, and a 4 cm by 4 cm square hole is cut from the middle. The remaining metal is shaded 20 cm 15 cm 8 cm 6 cm 4 cm 4 cm

What is the area of the metal that is left?

cm²

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Start with the full sheet. Two pieces are removed, and one of them is a triangle.

Question 9 of 10 · Triangles and rectangles: area and perimeter

A rectangular room measures 15 ft 6 in by 11 ft 9 in. Baseboard trim will go around the whole room (ignore the doorway). Trim is sold in 8-foot pieces.

What is the smallest number of pieces that must be bought?

Answer choices
Hint

Write each measurement in feet only (6 in is what part of a foot?). Then find the distance around.

Question 10 of 10 · Polygons: area and perimeter

No calculator

The base of a parallelogram is twice its height. The area of the parallelogram is 98 square inches.

What is the length of the base?

Answer choices
Hint

Let the height be h and write the base using h. Put both into A = bh.

Formula sheet

Area

Area of a square s = length of a side
A = s^2
Area of a rectangle l = length, w = width
A = lw
Area of a parallelogram b = base, h = height (straight up from the base, not the slanted side)
A = bh
Area of a triangle b = base, h = height
A = \tfrac{1}{2}bh
Area of a trapezoid b_1 and b_2 = the two parallel sides, h = height
A = \tfrac{1}{2}h(b_1 + b_2)
Area of a circle r = radius (half of the diameter); \pi \approx 3.14
A = \pi r^2

Perimeter and circumference

Perimeter of a square s = length of a side
P = 4s
Perimeter of a rectangle l = length, w = width
P = 2l + 2w
Perimeter of a triangle s_1, s_2, s_3 = the three side lengths
P = s_1 + s_2 + s_3
Circumference of a circle the distance around a circle; r = radius, d = diameter, \pi \approx 3.14
C = 2\pi r = \pi d

Surface area (SA) and volume (V)

p = perimeter of the base with area B; \pi \approx 3.14

Rectangular prism l = length, w = width, h = height
SA = 2lw + 2lh + 2wh \qquad V = lwh
Right prism B = area of the base, p = perimeter of the base, h = height
SA = ph + 2B \qquad V = Bh
Cylinder r = radius of the base, h = height
SA = 2\pi rh + 2\pi r^2 \qquad V = \pi r^2 h
Pyramid B = area of the base, p = perimeter of the base, s = slant height, h = height
SA = \tfrac{1}{2}ps + B \qquad V = \tfrac{1}{3}Bh
Cone r = radius of the base, s = slant height, h = height
SA = \pi rs + \pi r^2 \qquad V = \tfrac{1}{3}\pi r^2 h
Sphere r = radius
SA = 4\pi r^2 \qquad V = \tfrac{4}{3}\pi r^3

Data

Mean (average) add all the values of the data set, then divide by how many values there are
\text{mean} = \dfrac{\text{total of the values}}{\text{number of values}}
Median
the middle value when the data are in order; with an even number of values, it is the mean of the two middle values

Algebra

Slope of a line (x_1, y_1) and (x_2, y_2) = two points on the line
m = \dfrac{y_2 - y_1}{x_2 - x_1}
Slope-intercept form of a line m = slope, b = y-intercept (where the line crosses the y-axis)
y = mx + b
Point-slope form of a line m = slope, (x_1, y_1) = a point on the line
y - y_1 = m(x - x_1)
Standard form of a quadratic equation a, b, c are numbers and a \ne 0
y = ax^2 + bx + c
Quadratic formula solves ax^2 + bx + c = 0
x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}
Pythagorean theorem in a right triangle: a, b = the two legs, c = the hypotenuse (the longest side, across from the right angle)
a^2 + b^2 = c^2
Simple interest I = interest, P = principal (the amount saved or borrowed), r = rate per year as a decimal, t = time in years
I = Prt
Distance = rate × time d = distance, r = rate (speed), t = time
d = rt
Total cost
\text{total cost} = (\text{number of units}) \times (\text{price per unit})