Angles Β· Triangles Β· Area Β· Pythagorean Β· Circles Β· Perimeter
β‘ MEMORY POINT
Supplementary angles = add up to 180Β°
Complementary angles = add up to 90Β°
"S for Straight (180) Β· C for Corner (90)"
TOPIC 11 Β· Angle Relationships
11 Supplementary vs Complementary
π EXAMPLE
Two angles are supplementary. One is 110Β°.
β \(180Β° - 110Β° = 70Β°\) β the other angle
Two angles are complementary . One angle is 34Β°. What is the other?
A 146Β°
B 56Β°
C 66Β°
D 34Β°
β‘ MEMORY POINT
Triangle Angle Sum: Always 180Β°
\(\angle A + \angle B + \angle C = 180Β°\)
TOPIC 12 Β· Triangle Angles π₯ TRICKY
12 Finding the Missing Angle
π EXAMPLE
Triangle with angles 50Β°, 70Β°, and ?
β \(50 + 70 + x = 180\) β \(x = 60Β°\)
A triangle has angles of \(55Β°\) and \(82Β°\). What is the third angle?
A 137Β°
B 33Β°
C 43Β°
D 53Β°
β‘ MEMORY POINT
Area of Triangle = \(\dfrac{1}{2} \times base \times height\)
"Half of rectangle" β the height must be perpendicular!
TOPIC 13 Β· Area of Triangle
13 Area β Don't Forget the Half!
\[A = \frac{1}{2} \times b \times h\]
Find the area of a triangle with base = 10 cm and height = 7 cm.
A 70 cmΒ²
B 35 cmΒ²
C 17 cmΒ²
D 34 cmΒ²
β‘ MEMORY POINT
Pythagorean Theorem: \(a^2 + b^2 = c^2\)
c = hypotenuse (longest side, opposite the right angle)
TOPIC 14 Β· Pythagorean Theorem π₯ TRICKY
14 Finding the Hypotenuse
\[a^2 + b^2 = c^2\]
π EXAMPLE
Legs: 3 and 4 β \(3^2 + 4^2 = 9 + 16 = 25\) β \(c = \sqrt{25} = 5\)
A right triangle has legs of 5 and 12. Find the hypotenuse.
A 17
B 13
C \(\sqrt{17}\)
D 60
β‘ MEMORY POINT
Perimeter = add ALL sides
Rectangle: \(P = 2l + 2w\) Β· "Two lengths + Two widths"
TOPIC 15 Β· Perimeter
15 Rectangle Perimeter
\[P = 2l + 2w\]
A rectangle has length 9 m and width 4 m. Find the perimeter.
A 36 m
B 26 m
C 13 m
D 72 m
β‘ MEMORY POINT
Circle: \(A = \pi r^2\) Β· \(C = 2\pi r\)
Area uses rΒ² Β· Circumference uses r only!
TOPIC 16 Β· Circle Area π₯ TRICKY
16 Area of a Circle β Diameter Trap!
π EXAMPLE
Diameter = 10 β radius = 5
\(A = \pi r^2 = \pi \times 25 = 25\pi \approx 78.5\)
A circle has a diameter of 12 cm. Find its area. (Use \(\pi \approx 3.14\))
A 452.16 cmΒ²
B 37.68 cmΒ²
C 113.04 cmΒ²
D 144 cmΒ²
βοΈ r = d Γ· 2 = ?
β‘ MEMORY POINT
Vertical angles are EQUAL
They form an "X" β opposite angles match!
TOPIC 17 Β· Vertical Angles
17 Vertical Angles β Same or Different?
π EXAMPLE
Two lines cross β 4 angles form.
Angle 1 = 65Β° β Vertical angle (angle 3) = 65Β°
Adjacent angle (angle 2) = 180Β° β 65Β° = 115Β°
Two lines intersect. One angle is 72Β°. What is its vertical angle?
A 108Β°
B 18Β°
C 72Β°
D 90Β°
β‘ MEMORY POINT
Volume of Rectangular Prism: \(V = l \times w \times h\)
"Length Γ Width Γ Height β fill the box!"
TOPIC 18 Β· Volume
18 Volume of Rectangular Prism
\[V = l \times w \times h\]
Find the volume of a box with length 6 cm, width 4 cm, height 5 cm.
A 60 cmΒ³
B 148 cmΒ³
C 120 cmΒ³
D 240 cmΒ³
β‘ MEMORY POINT
Parallel lines cut by transversal:
Alternate interior angles = EQUAL
Co-interior (same-side) angles = 180Β°
TOPIC 19 Β· Parallel Lines & Transversals π₯ TRICKY
19 Alternate Interior Angles
π EXAMPLE
Two parallel lines are cut by a transversal.
One alternate interior angle = 115Β°
β Its alternate interior angle =
115Β° (equal!)
Parallel lines are cut by a transversal. One co-interior (same-side interior) angle is 65Β°. What is the other co-interior angle?
A 65Β°
B 25Β°
C 115Β°
D 90Β°
β‘ MEMORY POINT
Sum of interior angles of a polygon:
\((n - 2) \times 180Β°\) where n = number of sides
Triangle(3) = 180Β° Β· Quadrilateral(4) = 360Β° Β· Pentagon(5) = 540Β°
TOPIC 20 Β· Polygon Angles π₯ TRICKY
20 Interior Angle Sum of a Hexagon
\[\text{Sum} = (n - 2) \times 180Β°\]
π EXAMPLE
Pentagon (n = 5): \((5-2) \times 180Β° = 3 \times 180Β° = 540Β°\)
What is the sum of interior angles of a hexagon (6 sides)?
A 540Β°
B 1080Β°
C 720Β°
D 360Β°
π Amazing! You've completed all 20 problems!
Check your score below π