Download Angles notes - Int - Ysgol Uwchradd Caergybi

ANGLES Intermediate Revision
Acute Angle < 90°
Obtuse
90° - 180°
Reflex angle
180° - 360°
Angles within in
a full circle
half circle
quarter circle
three quarter circle
Right angle
90°
= 360°
= 180°
= 90°
= 270°
b
a
c
Angles around a point add to give 360°
a + b+ c = 360°
•
b
a
b
a
Angles on a straight line add to give 180°
a + b = 180°
Opposite angles are equal
a=b
Parallel lines
a
a
a
b
b
b
Corresponding angles are equal a = b
•
Alternative angles are equal a = b
Interior angles add to give 180° a + b =180°
a
Triangles
c
c
a
b
b
Sum of the angles in a Triangle =180°
a + b + c = 180°
•
Quadrilateral
d
In a Equilateral triangle
All sides and angles are equal
all = 60o
b
a
b
Isosceles triangle
Two angles and
sides are equal
a
Sum of the interior angles of a quadrilateral = 360°
a + b + c + d = 360°
c
Interior and Exterior Angles
Exterior angles of a polygon = 360° ÷ number of angles
Interior angle = 180° – exterior angle
Interior angle
180° – 60° = 120°
d
The exterior angle is equal to the
sum of the two opposite interior
angles a + c = d
POLYGONS
•
b
exterior angle
360° ÷ 6 = 60°