We made the letter C using a defined diagonal to shorten the code

typeface.py

@@ -13,7 +13,7 @@ from turtle import *
 from math import sqrt
 
 size=40
-
+diagonal=(size*sqrt(2))
 def draw_letter_a(unit):
     pass
 
@@ -21,7 +21,39 @@ def draw_letter_b(unit):
     pass
 
 def draw_letter_c(unit):
-    pass
+    penup()
+    forward(size*3)
+    pendown()
+    forward(size*4)
+    left(90)
+    forward(size*2)
+    left(90)
+    forward(size*3)
+    right(45)
+    forward(diagonal)
+    right(45)
+    forward(size*2)
+    right(45)
+    forward(diagonal)
+    right(45)
+    forward(size*3)
+    left(90)
+    forward(size*2)
+    left(90)
+    forward(size*4)
+    left(45)
+    forward(diagonal*2)
+    left(45)
+    forward(size*4)
+    left(45)
+    forward(diagonal*2)
+    penup()
+    right(135)
+    forward(size*3)
+    right(180)
+    pendown()
+
+
 
 def draw_letter_d(unit):
     penup()