In regular pentagon ABCDE, diagonal AC is drawn as shown. Given that each interior angle of a pentagon measures 108 degrees what is the measure of angle CAB?

Question

danjs · Answer

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danjs · Answer

bad drawing, but regular means all sides are the same length, so AB = BC, 

since ABC is an isocelese triangle, the two angles opposite AB and BC are the same

danjs · Answer

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danjs · Answer

Angle B is given as 108

angles u and v are the same measure

the total of u, v and 108 is 180 for the 3 angles of a triangle