Take any quadrilateral, say ABCD , Divide it into two triangles, by drawing a diagonal. You get six angles 1,2,3,4,5 and 6. Use the angle sum property of a triangle and argue how the sum of the measures of and amount to `180^@ + 180^@ = 360^@`.

Consider a concave quadrilateral ABCD, Split it into two triangles and find the sum of the interior angles.

Examine the table. (Each figure is divided into triangles and the sum of the angles deduced from that.) What can you say about the angle sum of a convex polygon with number of sides? 10

Examine the table. (Each figure is divided into triangles and the sum of the angles deduced from that.) What can you say about the angle sum of a convex polygon with number of sides? n

Examine the table. (Each figure is divided into triangles and the sum of the angles deduced from that.) What can you say about the angle sum of a convex polygon with number of sides? 7

Examine the table. (Each figure is divided into triangles and the sum of the angles deduced from that.) What can you say about the angle sum of a convex polygon with number of sides? 8

Take four congruent card-board copies of any quadrilateral ABCD, with angles as shown in the figures. Arrange the copies as shown in the figure, where angles angle1, angle2,angle3,angle4 meet at a point. What can you say about the sum of the angles angle1, angle2,angle3 and angle4 .

Take four congruent card-board copies of any quadrilateral ABCD, with angles as shown in the figures. Arrange the copies as shown in the figure, where angles angle1, angle2,angle3,angle4 meet at a point. What can you say about the sum of the angles angle1, angle2,angle3 and angle4 .

Without using pythogoras theorem,show that A(4,4),B(3,5) and C(-1,1) are the vertices of a right angled triangle.

The sum of the degree measures of the three angles of a triangle is 180. The measure of the 2nd angle exceeds that of the 1st by 8 and the measure of the 3rd angle is twice of that of the 2nd. Find the measure of each angle.

Express the following statements by equations : The sum of the degree measures of the three angles of a triangle is 180^@ . The measure of the 2nd angle is twice that of the 1st and exceeds the thrid angle by 40^@ .