Ch. 3 - Plane Geometry

Question 1

Complementary angles

Answer 1

Angles whose measures add up to 90°.

Question 2

Supplementary angles

Answer 2

Angles whose measures add up to 180°.

Question 3

Arc

Answer 3

A portion of a cirle’s edge.

degree/360 • Circumference = Arc

Question 4

Chord

Answer 4

A line segment connecting two distant points of a cirlce.

Question 5

Sector

Answer 5

A portion of a cirle’s area between two radii.

degree/360 • Area = Sector

Question 6

The Third Side Rule

Answer 6

The length of any side of a triangle must be between the sum and the differenece of the lengths of the other two sides.

Question 7

Area of an Equilateral Triangle

Answer 7

A = s²√(3)/4

Question 8

Area of a Triangle

Answer 8

A = 1/2 ab sinØ

This formula is useful when you know the lengths of two sides of a triangle (a and b), and the measure of the angle between them (Ø).

Question 9

Puthagorean Triplets

Answer 9

3-4-5

6-8-10

5-12-13

8-15-17

7-24-25

Question 10

45°-45°-90°

Answer 10

x : x : x√2

Question 11

30°-60°-90°

Answer 11

x : x√3 : 2x

Question 12

Area of a Parallelogram

Answer 12

A = bh

If you know the two adjacent sides of a parallelogram (a and b) and the angle between them (Ø), you can use the following formula:

A = ab sinØ

Question 13

Area of a Square

Answer 13

A = s²

A = d²/2

Question 14

Area of a Trapezoid

Answer 14

A = 1/2 (b₁ + b₂) h

Question 15

Sum of the Angles of a n-sided Polygon

Answer 15

Sum of Angles = (n – 2) x 180°

Question 16

While a central angle with a certain degree measure intercepts an arc of the same degree measure, an inscribed anlge intercepts an arc with twice the degree measure of the angle.

Answer 16

Question 17

Any angle inscribed in a semicircle is a right angle.

Answer 17

Question 18