Complementary Angles

Posted in Terms Defined

When the sum of the measures of two angles is 90°, the angles are called complementary angles.

For examples the following pairs are complementary:

(a) 30° and 60°

(b) 45° and 45°

(c) 10° and 80°

 When two angles are complementary, each angle is said to be the complement of the other angle. The '10° angle' is complement of the '80° angle'.

Range of Observations

Posted in Terms Defined

The difference between the highest and lowest observation is called the range of the observations.

For example, consider the following observations:

2, 10, 5, 34, 98, 54

The highest observation is 98 and the lowest observation is 2. 

So, the range of the observation is

= 98 - 2

= 96

Important Statements

Posted in Terms Defined

  • A factor of a number is an exact divisor of that number.
  • A number for which sum of all its factors is equal to twice the number is called a perfect number.
  • The numbers other than 1 whose only factors are 1 and the number itself are called Prime numbers.
  • Numbers having more than two factors are called Composite numbers.


Posted in Terms Defined

A fraction means a part of a group or of a region.

for example \(\frac{2}{3}\) is a fraction

where 2 is numerator and 3 is denominator.

Proper Fraction - In a proper fraction the numerator is always less than the denominator. For example \(\frac{4}{7}\), \(\frac{21}{43}\)

Improper Fraction - In a improper fraction the denominator is always less than the numerator. For example \(\frac{7}{4}\), \(\frac{43}{21}\)

Mixed Fractions - A mixed fraction has a combination of a whole and a part. For example \(3 \frac{1}{2}\), \(7 \frac{4}{7}\)

Rational Numbers

Posted in Terms Defined

A number which can be written in the form \(\frac{p}{q}\), where p and q are integers and q ≠ 0 is called a rational number.

For e.g.

\(\frac{-2}{5}\), \(\frac{6}{7}\)