T Madas Right Obtuse Acute angled Isosceles Equilateral

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Right Obtuse Acute angled Isosceles Equilateral Scalene ? ? Does not exist © T Madas

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The angles in a triangle add up to 180° © T Madas

The angles in a triangle add up to 180° © T Madas

The angles in a triangle add up to 180° © T Madas

Practice Angle Calculations with Triangles © T Madas

60° 100° 45° 70° 35° 45° 50° 55° 80° 45° 65° 25° 30° 115° 65° 25° 55° 120° 35° 70° 50° 35° © T Madas

70° 104° 48° 65° 33° 45° 52° 80° 47° 61° 29° 33° 109° 62° 24° 52° 117° 38° 77° 71° 51° 39° © T Madas

80° 101° 47° 60° 36° 43° 40° 53° 80° 48° 64° 26° 32° 110° 61° 23° 52° 117° 38° 71° 50° 40° © T Madas

50° 70° 40° 55° 70° 65° 40° 100° 65° 40° 45° 110° 45° 35° 20° 35° 80° © T Madas

Quick Test on Angle Calculations with Triangles © T Madas

60° 100° 45° 70° 35° 45° 50° 55° 80° 45° 65° 25° 30° 115° 65° 25° 55° 120° 35° 70° 50° 35° © T Madas

70° 104° 48° 65° 33° 45° 52° 80° 47° 61° 29° 33° 109° 62° 24° 52° 117° 38° 77° 71° 51° 39° © T Madas

80° 101° 47° 60° 36° 43° 40° 53° 80° 48° 64° 26° 32° 110° 61° 23° 52° 117° 38° 71° 50° 40° © T Madas

50° 70° 40° 55° 70° 65° 40° 100° 65° 40° 45° 110° 45° 35° 20° 35° 80° © T Madas

© T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 4 C 3 2 1 0 B A 1 2 3 4 5 6 © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 C 4 3 2 1 0 B A 1 2 3 4 5 6 © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. C 6 Mark on the grid another position for point C, so that triangle is still isosceles. 5 4 3 2 1 0 B A 1 2 3 4 5 6 © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 4 3 C 2 1 0 B A 1 2 3 4 5 6 © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 4 3 C 2 1 0 B A 1 2 3 4 5 6 © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 4 C 3 2 1 B A Mark on the grid another position for point C, triangle is isosceles and right angled. 0 1 2 3 4 5 6 so that © T Madas

An isosceles triangle ABC is drawn below, with the points A and B fixed and point C free to move. Mark on the grid another position for point C, so that triangle is still isosceles. 6 5 4 C 3 2 1 B A Mark on the grid another position for point C, triangle is isosceles and right angled. 0 1 2 3 4 5 6 so that © T Madas

© T Madas

Calculate the angle marked as x. 61° 21° 69° 29° 50° x © T Madas

© T Madas

Calculate the angle marked as x 50° 130° 20° 70° ° 0 x 3 © T Madas

© T Madas

Calculate the angle marked as x. 49° 41° 49° x © T Madas

© T Madas

Calculate three angles of the triangle 70 ° 140° 40 ° 70 ° Calculate the angle marked with x 55 ° 110° x 70 ° 55 ° © T Madas

© T Madas

Calculate the angle marked with x 292° x 68 ° 136° 44 ° 68 ° © T Madas

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Calculate the missing angles in each triangle 70° 50° 65° 55° © T Madas

© T Madas

One of the angles of an isosceles triangle is 64°. What are the sizes of the other two angles? [You must show that there are 2 different possibilities] 1 st possibility 2 nd possibility 52° 64 + 64 128 64° 180 – 128 52 58° 180 – 64 116 58° 116 ÷ 2 = 58° © T Madas

© T Madas