x < 90
acute
90 < x < 180
obtuse
x=90
right
180 < x < 360
reflex
x + y = 90
complementary
x + y = 180
supplementary
a + b = 180
adjacent angles on a straight line
a + b + c + d + e = 360
angles at a point
a = c, b = d (X)
vertically opposite angles
a = b (Z)
alternate angles, – // –
c = b (F)
corresponding angles, –//–
b + d = 180 (C)
interior angles, –//–
equilateral triangle
3 equal sides and 3 equal angles
isosceles triangle
2 equal sides and 2 equal angles
scalene triangle
all sides of different lengths; all angles are different
180 in a triangle
angle sum of a triangle
exterior = sum of interior opposite angles
exterior angle of a triangle
parallelogram
rectangle
rhombus
square
kite
trapezium
triangle
3 sided