45-45- 90 Triangles
Friday, November 15, 2013
10:20 AM
Slide
Notes
45-45-90 Triangles
Because the numbers for right triangles are
pretty easy to remember, you can
memorize the lengths of the sides of this
base triangle and then use proportions, or
you may remember the procedure better as
cross-multiply and divide, to scale up or
down to the triangle you are solving for.
Let's explore this alternative method for
finding the lengths of this triangle. We will
try to find x. We will set up our proportion
by deciding what will be on top and what
will be on bottom. We are given the
hypotenuse, so that needs to be one of
them and of course we need x to be the
other one because that is what we are
solving for. The first ratio will be from our
triangle we must memorize. It has the
square root of two as the hypotenuse and
the side that is comparable to x is 1.
Now we will get the values for the triangle
we are solving for put in. The hypotenuse is
7 and our variable is x.
Cross multiply and divide. We get 7 over
the square root of two.
Saxon 2_ 3rd ed Page 1
Now we will do y. The variable y is also
seven over the square root of two. It should
make sense that they would be the same
because in the triangle you are to
memorize, those particular legs are both 1.
They will always be the same length. Stay
aware of that and you can save some steps
as you work these types of problems.
Saxon 2_ 3rd ed Page 2