The temperature of a liquid increases by 2°C every minute when it is heated and takes 5 minutes to decrease by 3°C
before remaining at 30°C. Adam heats the liquid for
12 minutes and let the solution to cool down. How long does
the solution take to return to its original temperature?
A 7 minutes
B 8 minutes
C 14.4 minutes
D 40 minutes​

answer

d. 10

explanation

the distance from point y to wx is the height of the triangle.

using pythagoras theorem,

group similar terms to get,

this implies that,

take positive square root of both sides to get,

this implies that,

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.

inverse operation of addition