BASICS OF GEOMETRY TRIANGLES
TRIANGLES sosceles triangles A triangles with three congruent sides is called an equilateral triangle and each angle is 60 degrees A triangle with at least two congruent sides is called an isosceles triangle. If a triangle has two congruent sides, then the angles opposite the two sides are congruent. The converse is also true. 2 equal angles and 2 equal sides
Right-angled Triangle A triangle with an interior right angle is called a right triangle. The side opposite the right angle is called hypotenuse, the other two sides are called as legs In 90 We know the Pythagoras theorem which states that square of hypotenuse is equal to squares of other two sides.
Special Right Triangles 30-60-90 Right Triangle Isosceles Right Triangle 30 45 2a 48a 2a 90 45 90 60
Area of a triangle is bh/2 and the perimeter is sum of all the three sides. - The sum of any two sides must be greater than the third side and the difference of any two sides of triangle must be less than the third side (Triangle inequality theorem) Basic rules The exterior angle of a triangle is the sum of opposite interior angles (Exterior angle theorem).
Problem In the figure, AC-BC. Find the values of X and Y 125
col) 125 55
th of BC 62 then vohat is the los a) 1g b) 183 d) 1st 1&3 Sot) IRB 12B 2e 2(6 18 Total Area =ta +18
a) 6 and 10 au elan ths tuo sides eb a trargle xespeotinaly uo hich o tha olovuig coud be poindtrianqle Andirat all 20 24 27