Given:
a square with an area of a² is enlarged to a square with an area of 25a².
The side length of the smaller square was changed when The side length was multiplied by 5.
Area = (1a)² = a²
Area = 1a * 5 = 5a ⇒ (5a)² = 25a²
Correct answer is: distance from D to AB is 6cm
Solution:-
Let us assume E is the altitude drawn from D to AB.
Given that m∠ACB=120° and ABC is isosceles which means
m∠ABC=m∠BAC = 
And AC= BC
Let AC=BC=x
Then from ΔACD , cos(∠ACD) = 
Since DCB is a straight line m∠ACD+m∠ACB =180
m∠ACD = 180-m∠ACB = 60
Hence 

Now let us consider ΔBDE, sin(∠DBE) = 

Recall that distance = speed times time. Thus, time = distance / speed.
Here:
time = distance / speed = 0.8 km / 12 km/hr = 1/15 hr.
Note that 1/15 hr = 1/15 (60 min) = 4 minutes
(2,5)(1,3)
slope(m) = (3 - 5) / (1 - 2) = -2/-1 = 2 (2 units up, one unit to the right)
y - y1 = m(x - x1)....using (1,3)
y - 3 = 2(x - 1)....talia's last step is incorrect because she didn't sub in her slope of 2