Question 389298
Since angle A is 20 degrees,


1) Find the third angle (C)


{{{C=2A}}}
{{{C=2(20)}}}
{{{C=40}}}
so now we have the third angle, C , which is 40 degrees



since the properties of a triangle tell us that the sum of angles must equal to 180 degrees, we can now solve for the last angle

2) Solve for last angle


{{{A + B + C = 180}}}
{{{(20) + B + (40) = 180}}}
{{{B = 180 - 20 - 40}}}
{{{B=120}}}

so the 3 angles of the triangle are 20, 40, and 120 degrees