ELM Study Guide Geometry 1

Sum equals 90^o

Sum equals 180^o

Intersection forms right angle

When 2 lines are cut by 3rd line, 3rd line is a transversal

No equal sides & no equal angles

-2 equal sides

- If you know value of 1 equal side, you can find out value of all angles

- All sides & angles are equal

- Measure of each angle is 60^o

The side opposite of the right angle is call hypotenuse

- It is an equilateral triangle cut in middle

- The side opposite the 90^o angle is always twice as long as the side opposite the 30^o angle.

- The side opposite the 60^o angle is always √3 times as long as the side opposite the 30^o angle

- Lives a double life: it is both an isosceles & right triangle

- The side opposite the 90^o angle is always √2 times larger than the two equal sides that sit opposite the 45^o angles

c² = a² + b²

- Pythagorean Triples: {3,4,5}, {5,12,13}, {8,15,17}, {7, 24, 25}, {9, 40, 41}.

Similar - of the same shape (Proportional)

Two triangles that are IDENTICAL.

- Two triangles are congruent if they meet these:

Side-Side-Side(SSS)

Side-Angle-Side(SAS)

Angle-Side-Angle(ASA)

Sum of lengths of triangle;s three sides

1/2 Base x Height

Two-dimensional figure with 3 or more straight sides

Sum of lengths of its sides

• 180^o x (n-2)
• - Ex. Triangle 180^o x (1) = 180^o

4 sided figure(quadrilateral) whose opposite sides are parallel.

• - Opposite sides are equal in length
• - Opposite angles are equal
• - Adjacent angles are supplementary
• - Diagonals bisect eachother

Parallelogram where all 4 sides are equal in length

(Base x Height) well....(Base x Altitiude)

One pair of sides is parallel while other is not

A = 1/2 (b₁ + b₂) x h

2πr

πr²

Line segment that is wrapped AROUND the circle with 2 points

STRAIGHT line segment ACROSS the circle with 2 points