Area Unit

Question 1

What is the formula for area of a square?

Answer 1

A = S² ; Area = side squared

Question 2

What is the formula for area of a rectangle?

Answer 2

A = l × w (Area = length × width) or A = b × h (Area = base × height)

Question 3

What is the formula for perimeter of a square?

Answer 3

P = 4s (Perimeter = 4x side length)

Question 4

What is the formula for perimeter of a rectangle?

Answer 4

P = 2l + 2w (Perimeter = 2 × length + 2 × width) or P = 2b + 2h (Perimeter = 2 × base + 2 × height) or P = 2(l + w) (Perimeter = 2 × [length + width]) or P = 2(b + h) (Perimeter = 2 × [base + height])

Question 5

What is the formula for area of a parallelogram?

Answer 5

A = b × h (Area = base × height)

Question 6

What is the alternative formula for area of a parallelogram?

Answer 6

A = a × b × sinϴ

Question 7

How do you find the height in a parallelogram?

Answer 7

Draw in the altitude and use right triangle rules

Question 8

What is the formula for area of a triangle?

Answer 8

A = 1/2bh (Area = 1/2 × base × height)

Question 9

What is the alternative formula for area of a triangle?

Answer 9

A = 1/2absinϴ

Question 10

How do you find the height in the triangle?

Answer 10

Draw in the altitude to the base and use right triangle rules.

Question 11

How can you often find the base and height in a right triangle?

Answer 11

Use the legs.

Question 12

What is significant about the altitude of an isosceles triangle drawn from the vertex angle?

Answer 12

It is also a median and angle bisector.

Question 13

What is significant about the altitude of an equilateral triangle?

Answer 13

It creates two 30º-60º-90º triangles.k

Question 14

What is the special formula for area of a rhombus?

Answer 14

A = 1/2 × d₁ × d₂(Area = 1/2 × diagonal one × diagonal two)

Question 15

What is the formula for area of a trapezoid?

Answer 15

A = 1/2h(b₁ + b₂)
Area = 1/2 × height × sum of the bases

Question 16

How do you find the height of a trapezoid?

Answer 16

Draw in an altitude and use right triangle rules.

Question 17

What is the formula for area of a circle?

Answer 17

A = πr² , (A = π × radius²)

Question 18

What is the formula for circumference of a circle?

Answer 18

Circumference = 2π × r
or Circumference = π × diameter

Question 19

What is the formula for area of a sector?

Answer 19

S = A × ϴ/360 , Sector area = Area of circle × ϴ/360

Question 20

What is the formula for arc length?

Answer 20

l = c × ϴ/360 , arc length = circumference of circle × ϴ/360

Question 21

What is the formula for area of any regular polygon?

Answer 21

A = 1/2 × P × a , Area = 1/2 × Perimeter × apothem

Question 22

How do you find the apothem?

Answer 22

Draw in a radius and apothem that makes a right triangle and use right triangle rules

Question 23

What is significant about the apothem?

Answer 23

It is a segment bisector

Question 24

What is the general strategy used to find the area of a shaded region in a figure?

Answer 24

Find the area of the larger figure and the area of the smaller figure and subtract

Question 25

What is significant about the radius?

Answer 25

It is an angle bisector

Question 26

If two similar polygons have a scale factor of a:b, what is the ratio of the areas?

Answer 26

a² : b²

Question 27

If the areas of two similar polygons are in a ratio of a:b, what is the scale factor of the polygons?

Answer 27

√a : √b