Hillary is using the figure shown below to prove Pythagorean Theorem using triangle similarity: In the given triangle ABC, angle A is 90° and segment AD is perpendicular to segment BC.
B
Which of these could be a step to prove that BC2 = AB2 + AC?? (6 points)
By the addition property of equality, Ac? plus AD2 = AB multiplied by DC plus AD2.
By the addition property of equality, Ac? plus AD2 = BC multiplied by DC plus AD2.
By the addition property of equality, Ac? plus AB2= AB multiplied by DC plus AB?
By the addition property of equality, AC plus AB2-BC multiplied by DC plus AB2

Find the value of 1715⋅211.though these numbers aren't quite as nice as the ones from the example or the previous part, the procedure is the same, so this is really no more difficult. give the numerator followed by the denominator, separated by a comma.

The rate of decay of a radioactive substance depends upon the amount present initially. the mass y (mg) of the radioactive substance cobalt-60 present in a sample at time t (years) is represented by the exponential equation y=50e −0.1315 t . answer the following questions in complete sentences. 1. how does the exponential equation above compare to the equation for simple interest that is compounded continuously? explain the similarities. 2. what is the initial amount of cobalt-60 in the sample? 2. how much cobalt-60 is left after 8.4 years? show your work. 3. what would be the y-intercept of the graph? what does it represent? 4. after how many years will the amount of cobalt-60 left be 6.25 mg? explain what happens to the cobalt-60 after 50 years? 5. discuss some “real-world” examples and uses of cobalt-60

Precalculus question, image attached.