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-rw-r--r--ClassJune26.page18
1 files changed, 9 insertions, 9 deletions
diff --git a/ClassJune26.page b/ClassJune26.page
index eea5dff..9bb4ded 100644
--- a/ClassJune26.page
+++ b/ClassJune26.page
@@ -77,14 +77,14 @@ b\end{array}\right)\\
0\\
1\end{array}\right)\\
= a\cdot1+b\cdot i\\
- = a+bi\end{eqnarray*}
+ = a+bi$
Put another way, we are using $1$ and $i$ as basis vectors. For
-example, $
-\left(\begin{array}{c}
+example,
+$\left(\begin{array}{c}
3\\
2\end{array}\right)=3(\rightarrow)+2(\uparrow)=3+2i$
-and $
-\overset{2}{\nwarrow}=\left(\begin{array}{c}
+and
+$\overset{2}{\nwarrow}=\left(\begin{array}{c}
-\sqrt{2}\\
\sqrt{2}\end{array}\right)=-\sqrt{2}(\rightarrow)+\sqrt{2}(\uparrow)=-\sqrt{2}+\sqrt{2}i$
@@ -108,16 +108,16 @@ by some fixed complex number $\rho=r(\cos\theta+i\sin\theta)=a+bi$,
which, as we saw before, is a dilation by $r$ plus a rotation by
$\theta$. The distributive law says precisely that this is a linear
transformation of the plane, viewed as a two-dimensional vector space.
-And linear maps are given in rectangular coordinates by matrices:\[
-\left(\begin{array}{c}
+And linear maps are given in rectangular coordinates by matrices:
+$\left(\begin{array}{c}
x\\
-y\end{array}\right)\rightsquigarrow\left(\begin{array}{cc}
+y\end{array}\right)\mapsto\left(\begin{array}{cc}
a & c\\
b & d\end{array}\right)\left(\begin{array}{c}
x\\
y\end{array}\right)=\left(\begin{array}{c}
ax+cy\\
-bx+dy\end{array}\right).\]
+bx+dy\end{array}\right).$
What is the matrix corresponding to multiplication by $\rho$? Well,
the first column is the image of $\left(\begin{array}{c}
1\\