Answer:
A=25√3 cm^2
Explanation:
Since it is a regular triangle, all sides are equal to 10cm. The dotted line is a perpendicular bisector, which means that it seperates the triangle into two perfect halves. So a right triangle is formed. The bottom of the right triangle will be half of 10, and 10/2=5. So to find the missing side, use the pythagoreom theorem.
5^2+x^2=10^2
25+x^2=100
x^2=75
x= 5√3
The height of the triangle is found, so apply the formula for area:
A=1/2*5√3*10
A=25√3