Angles, lines and polygons Flashcards
What angle is a full turn?
360°
What angle is a half turn?
180°
What angle is a right angle?
90°
What is an obtuse angle?
(90°, 180°)
What is an acute angle?
(0°, 90°)
What is a reflex angle?
(180°, 360°)
If two straight lines pass through each other and you know one angle is a°, what are the other angles?
The angle opposite will also be a°. Then, to find the other angles, you can do 180° - a° to know both of the other angles.
If a line passes through a set of parallel lines, and we say the angles around each intersection is a, b, c, d, e, f, g, h from top to bottom, and we know the value of a, how do we find the other angles?
a = e which in turn means that a = d = h = e. Then, we can say that b = 180° - a. Therefore overall we can state that a = d = e = h and 180° - a = b = c = f = g.
What is an Equilateral triangle?
A triangle with three equal sides and three 60° angles.
What is an Isosceles triangle?
A triangle with two equal sides and two equal angles.
What is a Right-angled triangle?
A triangle with a right angle.
What is a Scalene triangle?
A triangle that isn’t Isosceles.
What do all the angles in triangles add up to?
180°, because if you draw a line parallel to the base of the triangle at the top, then the parallel line laws state that the angles in a triangle must add up to 180°.
What is a square?
A quadrilateral that has four equal sides and four 90° angles.
What is a rectangle?
A quadrilateral that has four 90° angles.
