The triangle sum theorem says all 3 interior angles must equal 180 degrees.
so, 43 + 35 = 78. [ 180 - 78 = 102 degrees for the missing angles shared by the 2 triangles.
102 + 18 = 120. [180 - 120 = 60}
leaving the measure of Angle A as 60 degrees.
Notice that if you go forward, the common ratio is 5. Each new term is found by mult. the previous term by 5.
If, on the other hand, you go backwards (terms decreasing), then you divide a term to find what the previous term was.
Here, divide 1 by 5 to find the first term. It's 1/5.
79.55449 your welcome this is totally wrong lol sos
