Geometry and Linear Equations Quiz

Study Notes

Triangle

Types of Triangles:
- By Sides:
  - Equilateral: All sides equal.
  - Isosceles: Two sides equal.
  - Scalene: All sides different.
- By Angles:
  - Acute: All angles < 90°.
  - Right: One angle = 90°.
  - Obtuse: One angle > 90°.
Properties:
- Sum of interior angles = 180°.
- Area = 0.5 × base × height.
- Pythagorean theorem: In right triangles, ( a^2 + b^2 = c^2 ) (where c is the hypotenuse).

Linear Equations in Two Variables

Standard Form: ( Ax + By + C = 0 )
- A, B, C are constants; A and B ≠ 0.
Slope-Intercept Form: ( y = mx + b )
- m = slope, b = y-intercept.
Graphing:
- To graph, identify the y-intercept and use the slope to find another point.
- Lines are either parallel (same slope) or intersecting (different slopes).
Solutions:
- A solution is an ordered pair (x, y) that satisfies the equation.
- The solution set can be infinite (dependent) or unique (independent).

Lines and Angles

Types of Lines:
- Parallel: Never intersect; same slope.
- Perpendicular: Intersect at 90°; product of slopes = -1.
Types of Angles:
- Acute: < 90°.
- Right: = 90°.
- Obtuse: > 90° and < 180°.
- Straight: = 180°.
Angle Relationships:
- Complementary: Sum = 90°.
- Supplementary: Sum = 180°.
- Vertical angles: Opposite angles that are equal when two lines intersect.

Heron's Formula

Used to calculate the area of a triangle when the lengths of all three sides are known.
Formula:
- Let the sides be ( a, b, c ).
- Compute the semi-perimeter ( s = \frac{a + b + c}{2} ).
- Area ( A = \sqrt{s(s-a)(s-b)(s-c)} ).
Conditions:
- Works for any type of triangle.
- Requires the triangle inequality to be satisfied: ( a + b > c ), ( a + c > b ), ( b + c > a ).

Triangle

Types of Triangles can be categorized based on sides or angles.
- By Sides:
  - Equilateral: All three sides are equal in length.
  - Isosceles: Two sides are equal in length, one side differing.
  - Scalene: All sides have different lengths.
- By Angles:
  - Acute: All angles are less than 90 degrees.
  - Right: One angle measures exactly 90 degrees.
  - Obtuse: One angle measures greater than 90 degrees.
Properties of triangles include:
- The sum of all interior angles in any triangle equals 180 degrees.
- The area can be calculated using the formula: Area = 0.5 × base × height.
- The Pythagorean theorem applies to right triangles: ( a^2 + b^2 = c^2 ), where ( c ) is the length of the hypotenuse.

Linear Equations in Two Variables

Standard Form: Represents equations as ( Ax + By + C = 0 ), where A, B, and C are constants, and A and B cannot be zero.
Slope-Intercept Form: Expressed as ( y = mx + b ), with ( m ) representing the slope of the line and ( b ) as the y-intercept.
Graphing Guidelines:
- Start by finding the y-intercept, then use the slope to locate another point on the line.
- Lines can be classified as parallel (if they share the same slope) or intersecting (if their slopes differ).
Solutions to an equation are expressed as ordered pairs (x, y) that satisfy the equation.
- Solutions can be infinite (dependent equations) or unique (independent equations).

Lines and Angles

Types of Lines include:
- Parallel Lines: These never intersect and have identical slopes.
- Perpendicular Lines: These intersect at a right angle (90 degrees), and the product of their slopes equals -1.
Types of Angles:
- Acute Angle: Measures less than 90 degrees.
- Right Angle: Measures exactly 90 degrees.
- Obtuse Angle: Measures more than 90 degrees but less than 180 degrees.
- Straight Angle: Measures exactly 180 degrees.
Angle Relationships:
- Complementary Angles: The sum of two angles is 90 degrees.
- Supplementary Angles: The sum of two angles is 180 degrees.
- Vertical Angles: Angles opposite each other when two lines intersect; these angles are equal.

Heron's Formula

Application: Used to determine the area of a triangle when the lengths of all sides are known.
Formula Steps:
- Identify the sides of the triangle as ( a, b, c ).
- First, calculate the semi-perimeter: ( s = \frac{a + b + c}{2} ).
- Area can be found using the formula: ( A = \sqrt{s(s-a)(s-b)(s-c)} ).
Conditions for Use:
- Applicable for any triangle type.
- Requires that the triangle inequality holds true: ( a + b > c ), ( a + c > b ), and ( b + c > a ).

Description

This quiz covers essential concepts of triangles, including their types, properties, and the Pythagorean theorem. Additionally, it explores linear equations in two variables, focusing on their standard and slope-intercept forms, as well as methods for graphing and determining solutions. Test your understanding of these fundamental topics in geometry and algebra.