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#6.1 #ncert #class7 #maths q1
median and altitudes || class7 maths || properties of triangles || ex 6.1 ncert class 7
ex6.1 | Ex 6.1 ncert class 7 maths || ex 6.1 || Exercise 6.1 medians and altitudes || exercise 6.1
ex 6.3 ncert class 7 deals with properties of triangles
6.3 exercise ncert maths class 7 triangles and its properties
1. The six elements of a triangle are its three angles and the three sides.
2. The line segment joining a vertex of a triangle to the mid point of its opposite side is
called a median of the triangle. A triangle has 3 medians.
3. The perpendicular line segment from a vertex of a triangle to its opposite side is
called an altitude of the triangle. A triangle has 3 altitudes.
4. An exterior angle of a triangle is formed when a side of a triangle is produced. At
each vertex, you have two ways of forming an exterior angle.
5. A property of exterior angles:
The measure of any exterior angle of a triangle is equal to the sum of the measures of
its interior opposite angles.
6. The angle sum property of a triangle:
The total measure of the three angles of a triangle is 180°.
7. A triangle is said to be equilateral if each one of its sides has the same length.
In an equilateral triangle, each angle has measure 60°.
8. A triangle is said to be isosceles if atleast any two of its sides are of same length.
The non-equal side of an isosceles triangle is called its base; thebase angles of an
isosceles triangle have equal measure.
9. Property of the lengths of sides of a triangle:
The sum of the lengths of any two sides of a triangle is greater than the length of the
third side.
The difference between the lengths of any two sides is smaller than the length of the
third side.
This property is useful to know if it is possible to draw a triangle when the lengths of
the three sides are known.
10. In a right angled triangle, the side opposite to the right angle is called the hypotenuse
and the other two sides are called its legs.
11. Pythagoras Property:
In a right-angled triangle,
the square on the hypotenuse the sum of the squares on its legs.
If a triangle is not right angled this property does not hold good. This property is
useful to decide whether a given triangle is right angled or not.