Tidy up

docs/lectures/graphics/04_transformations.md

@@ -33,7 +33,7 @@ $$
 v \cdot s = \begin{pmatrix} v_0 \cdot s_0 \\ v_1\cdot s_1 \end{pmatrix}
 $$
 
-We can scale triangles by scaling each of its vertices
+We can scale triangles by scaling each of their vertices
 
 ### Transformation Matrix
 
@@ -106,7 +106,7 @@ z:
 
 #### Combining Transformations
 
-For example if point $p$ needs to be scaled by $s=(2,1,1)$ and then translated by $t=(1,0,0)$
+For example, if point $p$ needs to be scaled by $s=(2,1,1)$ and then translated by $t=(1,0,0)$
 
 $$
 S = \begin{pmatrix}