Answer: 102°
Step-by-step explanation:
First and foremost, we should note that an isosceles triangle has two sides that are equal and that the sum of angles in a triangle equals to 180°.
Since we are told that the isosceles triangle has base angles that each measure 39°, the third angle will be:
t + 39° + 39° = 180°
t + 78° = 180°
t = 180° - 78°
t = 102°
The third angle is 102°.
6 : 10 = 3 : 5
24 : 40 = 3 : 5
36 : 60 = 3 : 5
42 : 70 = 3 : 5
A. 18 : 20 = 9 : 10 (incorrect)
B. 30 : 20 = 3 : 2 (incorrect)
C. 18 : 30 = 3 : 5 (correct)
D. 50 : 30 = 5 : 3 (incorrect)
The answer is C. 18 : 30
Hope this helps. - M
