Answer: 
Step-by-step explanation:
By definition, an Isosceles triangle has two equal sides and its opposite angles are congruent.
Observe the figure attached, where the isosceles triangle is divided into two equal right triangles.
So, in this case you need to use the following Trigonometric Identity:

In this case, you can identify that:

Substituting values, and solving for "x", you get:

Therefore, the length of BC rounded to nearest tenth, is:

The rate a computer works is 1/time. Working together, you add the rates.
Let new computer be x, old computer be y.
x = y - 7

Rounded to nearest tenth gives:
x = 23 hours
Choosing a color, number, or restaurant
For this case, the arithmetic sequence is given by:
an = 17n-1
Let's check it:
First week:
n = 1:
a1 = 17 (1) -1
a1 = 17-1
a1 = 16
Second week:
n = 2:
a2 = 17 (2) -1
a2 = 34-1
a2 = 33
Third week:
n = 3:
a3 = 17 (3) -1
a3 = 51-1
a3 = 50
Answer:
the explicit rule for the arithmetic sequence that defines the number of boxes of cereal sold in week n is:
an = 17n-1