Class 7 NCERT

Isoceles triangle

• sum of any 2 sides is always greater than the third side
• difference between the length of any 2 sides is smaller than the length of third side

Pythagoreas theorem

• side opposite to right angle is hypotenuse
• other 2 sides are its legs
• square of hypotenuse = sum of squares of legs

Class 7 - Arjun

Ex 10.1

• triangle and its properties - sides and angles and vertices
• types based on sides - 3
• types based on angles - 3
• special lines in triangles
• medians and centriod
  • line segment joining the vertices to the middle points of the opposite sides
  • medians meet at centroid
  • medians are concurrent
• altitudes and orthocentre
  • the perpendiculars drawn from the vertices to their opposite sides
  • meeting of altitudes are orthocentre
  • altitudes are concurrent
• perpendicular bisectors of sides and circumcentre
  • perpendicular bisectors of all 3sides meet at circum centre
  • bisectors are concurrent
• angle bisectors and incentre
  • angle bisectors are concurrent

Ex 10.2

• sum of angles in a triangle = 180
• exterior angle of a triangle and interior angles and their relation

Ex 10.3

• relation between sides of triangle
  • the sum of any two sides is always greater than the third side
  • the difference of any two side is always lesser than the third side
• relation between sides and angles opposite to them
  • in equilateral triangle, all sides and angles are equal
  • in isosceles triangle, angles opposite to equal sides are also equal
  • in scalene triangle,
    • the angle opposite to greatest side is always equal
    • the angle opposite to smallest side is always the smallest

Ex 10.4

• pythagoras theorem
• pythagorean triplets
• converse of pythagoras theorem