Triangle ACB and triangle ABD share one side AB. This means they have one side that is congruent; side AB
Angle ABD = Angle ABC
Angle BAC = Angle BAD
The pair of angles that are equal lie on the side AB
Hence, triangle ABC and triangle ABD are congruent by Angle-Side-Angle (ASA)
Answer: Second option
To determine the answer of Part A draw the equilateral triangle and the to determine the coordinates of of the third charge use that triangle.
To calculate the gravitational field strength in part B from each of the charges use the following equation.
E=kcq/r2
If you would add those values then you can use the symmetry about the y axis to make the vector addition a litter easier.<span />
Sqrt of 3......................................
