Presuming the circle is the whole, 1/4 + 1/2 is 3/4, or 0.75, so it is 75% of the circle.
Once the rock hits the ground, we know that its height will be equal to 0m
because of this, we can replace H(x) with 0

now all we have to do is get x by itself
so..

then


now take the square root of each side

2.857 seconds (rounded to the third decimal)
Answer:
In triangle ABC and triangle ADE
angle A = angle A (common)
anhle ABC = angle ADE
By AA , triangle ABC similar to triangle ADE
Thus
AB/AD = BC/DE
10/(10+x) = 6/10
60 + 6x = 100
6x = 40
x = 6.67
(-6)+4= -2
-2+(-10)= -12
Final answer= -12
Explanation: I’m smart