CHAPTER 3: MENSURATION Flashcards
What is the area of a rectangle?
Area= Length x Width
What is the area of a trapezium?
area= 1/2( a+b)h
What is the area of a kite?
1/2(a x b)
or 1/2 x (product of diagonals)
or
1 --- d1 x d2 2
What is the area of a triangle?
1/2 base x height
What is the formula used to find the height of a triangle when two sides and an included angle are known?
1/2 x b x a Sin C
b= base of entire triangle(length). a= length of the side of a triangle. When you split the triangle into two to find the height, 'a' is usually the hypotenuse. c= the included angle.
What is the area of a parallelogram?
Area= base x height
What if the height of the paralleogram not given?
area= ba sin 0 a= length of the side of a triangle. When you split the triangle into two to find the height, 'a' is usually the hypotenuse.
What is the circumference (perimeter) of a circle?
2πr
or πd
What is the ratio of a circle?
circumference ÷ diameter
What is the area of a circle?
A=πr2
What is the formula of the arc length of a circle?
Arc length= 0
——- x 2πr
360
What is the formula of sector area?
Sector area= 0
—— x πr2
360
CHORD:
- The area of a circle cut off by a chord is called a segment.
- The line from the centre of a circle to the midpoint of a chord bisects the chord at right angles.
- The line from the centre of a circle to the midpoint of a chord bisects the angle subtended by the chord at the centre of the circle.
How to find the area of a segment(minor arc)?
Area of segment= Area of sector - Area of triangle( at the centre of the circle)
What is the volume of a prism?
Volume= area of cross sectional area x length
