- If n is even , n(n+1)(n+2) is divisible by 24
- If an equation (i.e. f(x)=0 ) contains all positive co-efficients of any powers of x , it has no positive roots then. eg: x4+3x2+2x+6=0 has no positive roots.
- Product of any two numbers = Product of their HCF and LCM
- If two chords intersect, the product of the lengths of the two parts of one chord is equal to the product of the lengths of the parts of the other chord.
- The medians intersect at a point (called the centroid) that is two-thirds of the distance from each vertex to the midpoint of the opposite side
- A diameter drawn through a chord is perpendicular to the chord if and only if it bisects the chord and the arc.
- A number is divisible by 5 if and only if the last digit is divisible by 5.
- In any triangle a=b*CosC + c*CosB b=c*CosA + a*CosC c=a*CosB + b*CosA
- |x| + |y| >= |x+y| (|| stands for absolute value or modulus )
- If a trapezium can be inscribed in a circle it must be an isosceles trapezium (i.e. oblique sides equal).
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