Step-by-step explanation:
The slope of tangent line at a max or a minimum is 0,.
So using point slope formula.


Is the equation of a tangent line. This means we have a horizontal line at y= 4. Horizontal lines have a slope of 0.
Answer:

Step-by-step explanation:
Given
-- degree of freedom

Required
Determine the t-value
The given parameters can be illustrated as follows:

Where

So, we have:

To solve further, we make use of the attached the student's t distribution table.
From the attached table,
The t-value is given at the row with df = 28 and
is 3.673900
Hence, 
Get the equation of the line containing PQ using the point-slope formula:
<em>y</em> - (-2) = 3/2 (<em>x</em> - (-6))
Solve for <em>y</em> to get it in slope-intercept form:
<em>y</em> = 3/2 <em>x</em> + 7
so the <em>y</em>-intercept is (0, 7).
The line containing QR is then
<em>y</em> - 7 = -3/4 (<em>x</em> - 0)
or
<em>y</em> = -3/4 <em>x</em> + 7
The point R is on the <em>x</em>-axis, so its <em>y</em>-coordinate is 0. Plug in <em>y</em> = 0 and solve for <em>x</em> to get the other coordinate:
0 = -3/4 <em>x</em> + 7
3/4 <em>x</em> = 7
<em>x</em> = 4/3×7 = 28/3
So the point R has coordinates (28/3, 0).
Because of exterior angles theorem, y=39+65, so y=104
x and y are a linear pair, so they add up to 180. x=180-104, x=76
all angles in a triangle add up to 180, so 21+104+z=180. therefore, z=55
y=104
x=76
z=55