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Mathematics 7 Online
OpenStudy (anonymous):

In the figure below, CEF is an equilateral triangle. Points B, C and E are collinear; Points A, C and F are collinear; g = 40 degrees; and k = 45 degrees. Find angle j.

OpenStudy (anonymous):

75 105 60 45

OpenStudy (anonymous):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

CEF is an equilateral triangle, so that means all three sides of CEF are congruent also, all three angles of CEF are congruent

jimthompson5910 (jim_thompson5910):

what is the measure of each angle in triangle CEF?

OpenStudy (anonymous):

idk

jimthompson5910 (jim_thompson5910):

CEF is equilateral, so we know all three angles of CEF are congruent that means m = L = n also m+L+n = 180 m+m+m = 180 3m = 180 m = 60 each angle is equal to 60

OpenStudy (anonymous):

so i add 60

jimthompson5910 (jim_thompson5910):

thats part of it

jimthompson5910 (jim_thompson5910):

what is the measure of angle i ?

jimthompson5910 (jim_thompson5910):

hint: angle i and angle L are vertical angles

OpenStudy (anonymous):

60

jimthompson5910 (jim_thompson5910):

good

jimthompson5910 (jim_thompson5910):

since B, C, E are collinear, ie they fall on the same line this means i+j+k = 180 the three angles form a straight angle (aka a straight line)

jimthompson5910 (jim_thompson5910):

we know i = 60 k = 45 plug them into i+j+k = 180 and solve for j

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

i got 105

jimthompson5910 (jim_thompson5910):

60+45 = 105

jimthompson5910 (jim_thompson5910):

so you should have 105+j = 180

jimthompson5910 (jim_thompson5910):

you haven't fully isolated j yet though

OpenStudy (anonymous):

i got 75

jimthompson5910 (jim_thompson5910):

j = 75 is the answer

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