Step-by-step explanation:
The upstream speed is S / t₁, and the downstream speed is S / t₂.
If we say f is the speed of the fish in calm water, and r is the speed of the river, then:
f − r = S / t₁
f + r = S / t₂
If we say T is the time it takes to cross the river, then the speed perpendicular to the river is ℓ/T, the speed parallel to the river is r, and the overall speed is f.
Using Pythagorean theorem:
f² = (ℓ/T)² + r²
f² − r² = (ℓ/T)²
(f − r) (f + r) = (ℓ/T)²
(S / t₁) (S / t₂) = (ℓ/T)²
S² / (t₁ t₂) = (ℓ/T)²
(t₁ t₂) / S² = (T/ℓ)²
√(t₁ t₂) / S = T/ℓ
T = ℓ√(t₁ t₂) / S
Answer:
60
Step-by-step explanation:
As we have all the required values we need, Now we can put them in a simple mathematical formula as below:
STEP 172 = 120% × Y
STEP 272 =
120
100
× Y
Multiplying both sides by 100 and dividing both sides of the equation by 120 we will arrive at:
STEP 3Y = 72 ×
100
120
STEP 4Y = 72 × 100 ÷ 120
STEP 5Y = 60
Finally, we have found the value of Y which is 60 and that is our answer.
You can easily calculate 72 is 120 percent of what number by using any regular calculator, simply enter 72 × 100 ÷ 120 and you will get your answer which is 60
U = - 4 i + 1 j
v = 4 i + 1 j
| u | = √ (-4)² + 1² = √ 17
| v | = √4² + 1² = √ 17
| u + v | = √(u + v)²=
= √( u² + 2 u v + v² )= ...
cos ( u, v ) = (-16+1) / (|u| |v|) = -15/17
...= √(17 + 2 · √17 · √17 · ( -15/17) +17) =
= √ 34 - 30 = √ 4 = 2
Answer: C ) 2
Answer:
b
Step-by-step explanation:
