If one side of a cyclic quadrilateral is produced, then the exterior angle is equal to the interior opposite angle.

(Exterior Angle Theorem): If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the two interior opposite angles. GIVEN : A triangle A B C,D is a point of B C produced, forming exterior angle /_4. TO PROVE : /_4=/_1+/_2 i.e. , /_A C D=/_C A B+/_C B Adot

If the exterior angle of a quadrilateral formed by producing one of its sides is equal to the interior opposite angle, prove that the quadrilateral is cyclic.

If two sides of a cyclic quadrilateral are parallel , prove that the other two sides are equal

If two opposite sides of a cyclic quadrilateral are equal, then the other two sides are parallel.

If two sides of a cyclic quadrilateral are parallel, prove that the remaining two sides are equal and the diagonals are also equal. OR A cyclic trapezium is isosceles and its diagonals are equal.

A quadrilateral is parallelogram if its opposite angles are equal.

Which of the following statements are true (T) and which are false (F): Sum of the three angles of a triangle is 180^0 A triangle can have two right angles. All the angles of a triangle can be less than 60^0 All the angles of a triangle can be greater than 60^0 All the angles of a triangle can be equal to 60^0 A triangle can have two obtuse angles. A triangle can have at most one obtuse angles. In one angle of a triangle is obtuse, then it cannot be a right angled triangle. An exterior angle of a triangle is less than either of its interior opposite angles. An exterior angle of a triangle is equal to the sum of the two interior opposite angles. An exterior angle of a triangle is greater than the opposite interior angles

One angle of a quadrilateral is 180^0 and the remaining three angles are equal. Find the three equal angles.

theorem 1 (Exterior angle sum property) if the sides of quadrilateral are produced in order the sum of four exterior angles so formed is 360^@ .

Find the measure of the angles of a triangle which has one of its exterior angles of 120^(@) and the two interior opposite angles in the ratio 1:2.