Let speed of the boat in still water = x miles per hour
Let speed of the current = y miles per hour
When water and current both flow in same direction then effective speed will be sum of both speeds that is (x+y)
now plug the given values in formula speed=distance/time
we get equation:
(x+y)=160/8
or x+y=20...(i)
When water and current both flow in opposite direction then effective speed will be difference of both speeds that is (x-y)
now plug the given values in formula speed=distance/time
we get equation:
(x-y)=160/40
or x-y=4
or x=4+y...(ii)
plug value of x into (i)
4+y+y=20
4+2y=20
2y=16
y=8
plug value of y into (ii)
x=4+8=12
Hence final answer is given by:
Speed of the boat in still water = 12 miles per hour
Speed of the current = 8 miles per hour
Answer:
O A.
Step-by-step explanation:
<u>Option A</u> identifies two angles (sufficient for similarity) and one side, sufficient (with similarity) for congruence. The applicable congruence theorem is AAS.
<u>Option B</u> identifies two sides and the angle not between them. The two triangles will be congruent in that case only if the angle is opposite the longest side, which is <u>not true</u> in general.
<u>Option C</u> same deal as Option A.
<u>Option D</u> identifies three congruent angles, which will prove the triangles similar, but not necessarily congruent.
