Question

Class 9th
Mathematics
Chapter 7 - Triangles
Formulas Needed . Give 1 example for each Formuals

Note : Don't copy, Don't spam .

Quality answer with good explanation will be Brainliest .​

Answer 1

Step-by-step explanation:

Triangles:-

1. A simple closed figure bounded by three linesegments is called a triangle.

2. A triangle has 3 sides , 3 angles and 3 vertices.

3. The parts of a triangle = 6. They are 3 sides and 3 angles

4. There are three types of triangles based on its sides. They are Equilateral,Isosceles and Scalene triangles

5.There are 3 types of triangles based on their measure of angles. They are Acute angled triangle , Obtuse angled triangle and Right angled triangle.

6. If all sides are equal then it is an equilateral triangle.

Ex: 6 cm, 6cm,6cm

7.Each angle of an equilateral triangle is 60°

8. If two sides of a triangle are equal then it is an Isosceles triangle.

Ex:. 5cm , 5cm ,4cm

9. In an Isosceles triangle,The angles opposite to equal sides are equal.

Ex : In ∆ABC, AB = AC=> angle B= angle C

10. In a triangle The sides opposite to equal angles are equal.

11.In a triangle , The side opposite greatest angle is longer.

12.In a triangle , The side opposite to smallest angle is shorter.

13.If one angle is obtuse angle then it is called an obtuse angled triangle

Ex:100°,50°,30°

14. If one angle is right angle then it is called a right angled triangle

Ex:-90°,50°,40°

15.If all angles are acute then it is called an acute angled triangle.

Ex:(50°,60°,70°)

16.Area of a triangle when base and height is given (1/2)bh sq.units

17. Area of an Isosceles trianagle is

(b/4)√(4a^2-b^2) sq.units

18. Area of an equilateral triangle is (√3/4)a^2 sq.units

19. Area of a right angled triangle = (1/2)ab sq.units

20. 3 independent measurements are needed to construct a triangle.

21.The sum of any two sides of triangle is greater than the third side.

22.The difference between any two sides of a triangle is less than the third side.

23. 21 and 22 points are called inequalities of a triangle . These helps whether Given three measurements forms a triangle or not .

24.The number of medians can be dream in a triangle = 3

25.Hipparacus was the first scientist who tells the relationship between the sides and angles in a triangle.