Download Triangle Basics

Triangles
• Triangle: a figure formed when 3
noncollinear points are connected by
segments.
• Components of a triangle: B
– Vertices: A, B, C
– Sides: AB, BC, AC
– Angles: A, B, C
A
C
Triangles can be classified by Angles:
1) Acute - 3 acute angles
2) Obtuse - 1 obtuse angle
B
3) Right - 1 right angle
B
A
C
B
A
C
A
C
•
•
•
•
or Sides:
1) Scalene - no sides congruent
2) Isosceles - at least 2 sides congruent
3) Equilateral - all sides congruent
A
C
C
B
A
A
C
B
B
Focus on Isosceles Triangles
• Vertex angle: the angle formed
by the congruent sides
C
C
• Base: the side opposite the
vertex angle
AB
• Legs: the two congruent sides
and
• Base Angles: the two angles
formed by the base and one of
the congruent sides
AC
BC
 A and B
A
B
Application
Find d and the measure of each side of
equilateral triangle KLM if
KL = d + 2
LM = 12 - d
KM = 4d - 13
Triangles on the Coordinate Plane
Classify RST by sides
R (-1, -3)
S (4, 4)
T (8, -1)
d
 x2  x1    y2  y1 
2
2