Area Unit Flashcards
What is the formula for area of a square?
A = S² ; Area = side squared
What is the formula for area of a rectangle?
A = l × w (Area = length × width) or A = b × h (Area = base × height)
What is the formula for perimeter of a square?
P = 4s (Perimeter = 4x side length)
What is the formula for perimeter of a rectangle?
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])
What is the formula for area of a parallelogram?
A = b × h (Area = base × height)
What is the alternative formula for area of a parallelogram?
A = a × b × sinϴ
How do you find the height in a parallelogram?
Draw in the altitude and use right triangle rules
What is the formula for area of a triangle?
A = 1/2bh (Area = 1/2 × base × height)
What is the alternative formula for area of a triangle?
A = 1/2absinϴ
How do you find the height in the triangle?
Draw in the altitude to the base and use right triangle rules.
How can you often find the base and height in a right triangle?
Use the legs.
What is significant about the altitude of an isosceles triangle drawn from the vertex angle?
It is also a median and angle bisector.
What is significant about the altitude of an equilateral triangle?
It creates two 30º-60º-90º triangles.k
What is the special formula for area of a rhombus?
A = 1/2 × d₁ × d₂(Area = 1/2 × diagonal one × diagonal two)
What is the formula for area of a trapezoid?
A = 1/2h(b₁ + b₂)
Area = 1/2 × height × sum of the bases
How do you find the height of a trapezoid?
Draw in an altitude and use right triangle rules.
What is the formula for area of a circle?
A = πr² , (A = π × radius²)
What is the formula for circumference of a circle?
Circumference = 2π × r
or Circumference = π × diameter
What is the formula for area of a sector?
S = A × ϴ/360 , Sector area = Area of circle × ϴ/360
What is the formula for arc length?
l = c × ϴ/360 , arc length = circumference of circle × ϴ/360
What is the formula for area of any regular polygon?
A = 1/2 × P × a , Area = 1/2 × Perimeter × apothem
How do you find the apothem?
Draw in a radius and apothem that makes a right triangle and use right triangle rules
What is significant about the apothem?
It is a segment bisector
What is the general strategy used to find the area of a shaded region in a figure?
Find the area of the larger figure and the area of the smaller figure and subtract
