Homework: 1.5/1-14, 17-21, Quiz Friday on Lesson 1.3 – 1.5

 To assume something is to accept it as true without facts or proof.  When looking at a diagram, be careful not to assume anything

 Lines are straight  If two lines intersect, they intersect at one point  Points on a line are collinear  All points shown in a diagram are coplanar unless additional planes are shown

Just because they look : pparallel ›t›two lines or segments are NOT necessarily parallel pperpendicular ›t›two lines are NOT necessarily perpendicular CCongruent ›p›pairs of angles, segments, or polygons are NOT necessarily congruent

All CONGRUENT, PARALLEL, PERPENDICULAR parts MUST be MARKED

 A triangle has three sides and three angles  The three angles always add to 180°  There are special names given to triangles that tell how many sides or angles are equal.  There can be 3, 2 or no equal sides/angles : › Sides: Equilateral, Isosceles and Scalene › Angles: Acute, Right, Obtuse, and Equiangular

Equilateral Triangle Three equal sides Isosceles Triangle Two equal sides Scalene Triangle No equal sides

Acute Triangle All angles are between 0°and 90° Right Triangle Has exactly one right angle (=90°) Obtuse Triangle Has one angle between 90° and 180° Equiangular Triangle Three equal angles, always 60°

 Sometimes a triangle will have two descriptive names.  One for angles & one for sides For example:  Right Isosceles Triangle › It has a right angle (90°), and also two equal angles  Can you guess what the measure of the equal angles are?

 Scalene right triangle?  Obtuse acute triangle?  Equiangular scalene triangle?  Isosceles right triangle?  Equilateral obtuse triangle?  YES  NO  YES  NO

 Sketch › To create the picture with only a pencil; freehand  Draw › To use measuring tools: ruler and protractor  Construct › To use construction tools: compass and straightedge These terms will determine what tools, if any, you are required/allowed to use.

1. 2.

A M N U Y O P 1. 2.

 ΔBAD with BA = 2.5 cm, m <A = 75˚  Right scalene ΔHOP with right angle P, PO = 4cm, PH = 2cm

A D B 75˚ 2.5cm H P O 4cm 2cm 3. 4.