Triangle ABC is an isosceles triangle. m

Question

Triangle ABC is an isosceles triangle. m<A=42. Find the m<C.
A.42°
B.69°
C.74°
D.132°

anonymous · Answer

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owlcoffee · Answer

Well, by definition, an isoceles triangle has two equal sides, and all the angles are 60º

owlcoffee · Answer

oh, i'm sorry, an isoceles is that has a pair of equal sides and equal angles.

anonymous · Answer

You were thinking of an equalateral triangle.

anonymous · Answer

so its either A/B/C because D is larger then 90 degrees.

anonymous · Answer

and this triangle is not a right triangle

jdoe0001 · Answer

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what do you think about the other 2 angles?
2 sides are equal, the angles they make will be ?

anonymous · Answer

42

anonymous · Answer

? that was my first guess. but i felt like it was wrong.

jdoe0001 · Answer

if AC = AB
then the angles they make at the bottom, will be equal

jdoe0001 · Answer

so, A is 42
sum of internal angles is 180
so, what do you think you'd get for the other 2 equal fellows?

venomblast · Answer

THE ANSWER IS B

anonymous · Answer

so 42 is both of the angles ?

venomblast · Answer

i will explain

anonymous · Answer

ok

venomblast · Answer

if angle A is 42 degrees.  you will need to know what is angle B and C. You should know by now that a triangle need to be 180 degrees. the clue you got on the picture above show that line AB and AC have the same measurement

anonymous · Answer

yes! 180 degrees. i was thrown off earlier because someone told me it had to be 60..it makes sense now. Thanks. :)

venomblast · Answer

an icosles triangle has 2 of the same angle and side. therefore. if you subtract 180 from 42 you will get 138. then divide by 2 and will get 69 for both side

venomblast · Answer

No problem! Love to help

anonymous · Answer

180-42=138
-------------
2
=
69 <- like that?

anonymous · Answer

69+42+42= 180

venomblast · Answer

yea. you divide by two because you have to unknown angles/side

venomblast · Answer

no 69+69+42=180

venomblast · Answer

not 42.

anonymous · Answer

opps* 42+42 typo. :/

anonymous · Answer

D: you kno what i mean.

venomblast · Answer

haha it ok. Remember an isosceles triangle has 2 of the same side and angles, and one different and MUST ADD UP TO 180

anonymous · Answer

everywhere i looked the only info given was that it had 2 equal sides. I couldnt firgure out the 180 part.. :/ ..Anyways thank! (:

venomblast · Answer

just remember, all triangle should be equal to 180 in angles

anonymous · Answer

kk. thx