Presentation on theme: "9.5 Angles and Triangles p.551.. D E F Name the angle in five different ways. Angle DEF, angle FED, DEF, FED, or E."— Presentation transcript:
9.5 Angles and Triangles p D E F Name the angle in five different ways. Angle DEF, angle FED, DEF, FED, or E
.. Name the angle in five different ways. Angle PQR, angle RQP, PQR, RQP, or Q P Q R
Classifying Angles p.553 An angle whose measure is 90 o. An angle whose measure is 180 o.... CDE Right angle: Straight angle:
An angle whose measure is greater than 0 o and less than 90 o. An angle whose measure is greater than 90 o and less than 180 o. Acute angle: Obtuse angle:
Classify the angles as right, straight, acute or obtuse.... CDE Straight angle Right angle Acute angle Obtuse Angle
Complementary Angles p. 554 Two angles are complementary if the sum of their measures is 90 o. Each angle is called a complement of the other. Find the measure of a complement of the angle o o o 72 o 15 o 45 o
Supplementary Angles p. 555 Two angles are supplementary if the sum of their measures is 180 o. Each angle is called a supplement of the other. Find the supplement of the angle given o o o 142 o 23 o 90 o
Triangles p. 555 A triangle is a polygon made up of three segments, or sides. A triangle with vertices A, B, and C can be named ABC. AB C D E F G H I
Types of Triangles p. 556 Equilateral triangle - Isosceles triangle – Scalene triangle – All sides are the same length. Two or more sides are the same length. All sides are of different lengths.
Types of Triangles p. 556 Right triangle – Obtuse triangle – Acute triangle – One angle is a right angle. One angle is an obtuse angle. All three angles are acute.
Sum of the Angle Measures of a Triangle In any triangle ABC, the sum of the measures of the angles is 180 o. A B C 65 o 24 o Find the measure of angle A. x + 65 o + 24 o = 180 o x + 89 o = 180 o x = 180 o – 89 o x = 91 o x