The vertex of ∠𝑨𝑩𝑪 is ●B

symbolic notation:∥

So, a ∥ 𝑏

symbolic notation:⊥

So, c ⊥ 𝑑

Circle

The set of all points equidistant from a point in a plane

congruent

Two figures, segments, triangles, etc. that have the same size, same shape, same measure

∆PQR ≅ ∆LJK

symbolic notation:≅

acute angle

an angle whose measure is less than 90ᴼ

40ᴼ AWWW… Such a CUTE little angle!

symbolic notation:m∠A = 40ᴼ

A

right angle

an angle whose measure is exactly 90ᴼ

symbolic notation:m∠B = 90ᴼ

B

obtuse angle

an angle whose measure is greater than 90ᴼ

symbolic notation:m∠C = 120ᴼ

C120ᴼ

(obtuse angle)

straight angle

an angle whose measure is exactly 180ᴼ

symbolic notation:m∠ABC = 180ᴼ

BA C

HINT: THERE IS ONLY 1 STRAIGHT ANGLE…(thus a straight angle is different from supplementary angles!!!)

two angles whose sum is equal to 90ᴼ

12

m∠1 + m∠2 = 90ᴼ

12

m∠1 + m∠2 = 180ᴼ

two angles whose sum is equal to 180ᴼ

two angles that share a common ray

C

B

AD

Vertical Angles

two angles that are opposite of each other and share a common vertex

A

B

C

D

E

an angle that lies on the exterior of a figure

BA

C