Lesson 10. Isosceles and equilateral trianqles

EXAMPLE:

a = 73⁰  (isosceles triangle)

b + 73⁰ + 73⁰ = 180⁰  (angles in a triangle add up to 180)

b = 34⁰

EXAMPLE:

p = 49⁰  (vertically opposite)

q = p = 49⁰  (isosceles triangle)

r + 49⁰ + 49⁰ = 180⁰  (angles in a triangle add up to 180⁰)

r = 82⁰

Angle proof.

Prove that triangle ABC is isosceles.

Give all your reasons clearly.

Test lesson 10

• Test 1
• Test 2
• Test 3