Answer:
35/37
Step-by-step explanation:
In this question, we are to calculate the ratio that represents the cosine of angle O
Firstly, please check attachment for diagram of the triangle.
Mathematically, the trigonometric term Cos means the ratio of the length of the adjacent to that of the hypotenuse
The hypotenuse is the longest length which is 37 which represents the length ON
The side adjacent to angle O is the side OP which is 35
Thus, the ratio representing the cosine of angle O is 35/37
Given that,
A motorboat travels 165 kilometers in 3 hours going upstream and 510 kilometers in 6 hours going downstream
Therefore,
Upstream distance = 165 km
Upstream time = 3 hours
<h3><u>Find upstream speed:</u></h3>Thus upstream speed is 55 km per hour
Downstream distance = 510 km
Downstream time = 6 hours
<h3><u>Find downstream speed:</u></h3>Thus downstream speed is 85 km per hour
<em><u>If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then</u></em>
Speed downstream = u + v km/hr
Speed upstream = u - v km/hr
Therefore,
u + v = 85 ----- eqn 1
u - v = 55 ----- eqn 2
Solve both
Add them
u + v + u - v = 85 + 55
2u = 140
u = 70
<em><u>Substitute u = 70 in eqn 1</u></em>
70 + v = 85
v = 85 - 70
v = 15
Thus rate of the boat in still water is 70 km/hr and rate of the current is 15 km/hr
