Please help!!! SAT QUESTION! Urgent homework, help!

SAT

1 answer:

jekas [21]4 years ago

3 0

Answer:

A. 5/√89

Explanation:

Before I explain the answer, I want to point out that finding the length of AC isn't necessary. I will explain this in a little bit.

Angle AEB is part of the triangle AEB. We know that one of its angles, ABE, is 90 degrees. We also know that the sum of every triangle's total angles is 180 degrees. Upon further investigation, you can see that you can solve for angle BAE with the given lengths of CD and AD. In order to know this, you need to know S(o/h)C(a/h)T(o/a). With the angle being BAE, CD and AD would be the opposite and adjacent sides, respectively. This means we will use T(o/a), which means tanθ =o/a. (Now going back to why finding the length of AC isn't necessary- finding an angle needs only one of S(o/h)C(a/h)T(o/a), if we already have the needed values for one of them, we don't need to take an unnecessary step to find the extra value.)

Anyway, to isolate θ in the equation tanθ=o/a, we take the inverse tan of o/a. This might sound confusing, but basically, using the inverse of tan is basically like multiplying both sides by tan to cancel it on one side. Inverse tan looks like this: tan^-1, tan to the power of negative 1.

Plug in 5 (opposite) and 8 (adjacent) into our equation.

<em>tanθ=o/a</em>

<em>tanθ=5/8</em>

<em>θ=tan^1(5/8)</em>

<em>θ=32.00538321</em>

Now we know angle BAE is 32 degrees. Now add it to the angle ABE and subject the sum from 180.

<em>32.00538321+90=122.0053832</em>

<em>180-122.0053832=57.99461679</em>

Angle AEB is 57.99461679 degrees. Now all we have to do is find cos(57.99461679).

<em>cos(57.99461679)=0.52999894</em>

For choice A, 5 divided by √89 is also 0.52999894, therefore it is correct.

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You mix 2 moles of hbr with 3 moles of koh in enough water to make 1 l of solution. What is the ph of your final solution?.

siniylev [52]

Taking into account the definition of pH and pOH, limiting reagent and reaction stoichiometry, the pH of the final solution is 14.

<h3>Limiting reagent and excess of moles.</h3>

Hydrobromic acid and potassium hydroxide react in a 1:1 mole ratio to produce aqueous potassium bromide and water, following the reaction:

HBr + KOH → KBr + H₂O

So, if you mix equal numbers of moles of each reactant, both the acid and the base will be completely consumed.

But in this case you mix 2 moles of HBr with 3 moles of KOH.

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

In this case, as the reaction has a 1:1 mole ratio hydrobromic acid will act as the limiting reagent, and it will be completely consumed before all the moles of potassium bromide are consumed, so there will be an excess of moles of potassium bromide.

After the reaction is complete, the resulting solution will contain an excess of moles of potassium bromide calculated as, considering that when 2 moles of hydrobromic acid are consumed, 2 moles of potassium hydroxide are consumed:

3 moles that you had at the beginning of the reaction - 2 moles that react= 1 mole of potassium bromide

<h3>Definition of molarity</h3>

Molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

$Molarity= \frac{number of moles}{volume}$