The height of triangle is 7 units and base of triangle is 14 units
Solution:
The area of triangle is given by formula:

Where,
"b" is the base and "h" is the height of triangle
Given in question that,
Area = 49 square units
Also given that, base of a triangle is twice its height
Base of triangle = twice the height
b = 2h
Substituting the values in formula,

Since, height cannot be negative, ignore -7
The solution is h = 7
Substitute h = 7 in b = 2h
b = 2h
b = 2(7)
b = 14
Thus height of triangle is 7 units and base of triangle is 14 units