If you draw a diagonal from upper left to lower right, you divide the figure into two triangles. One is a 3-4-5 right triangle (with area = (1/2)*3*4 = 6). The other is a 5-5-4 isosceles triangle.
The altitude of the isosceles triangle (upper left vertex to side 4) can be found from the Pythagorean theorem as
.. altitude = √(5^2 -2^2) = √21
So, the area of the isosceles triangle is
.. (1/2)*4*√21 = 2√21
The sum of the areas of the two triangles matches selection C.
when it tells you what R is then you show a number line with -4 less then R
Let's say that the unknown value here is c. Although we are given two points on the line, it is only necessary to use one as there is only one unknown value, so let's say we choose the point (6, -12) and substitute this into the equation:
-12 = 1(6) - c
-12 - 6 = -c
-18 = -c
c = 18
Thus the equation for the line is y = 1x - 18
