What is the missing statement in step 3 of the proof?
given: 21 is complementary to 22.
22 is complementary to 23.
prove: m21=m23
omz1 = m22
m21+ m22 = 90°
m22 = m 23
m22+ m23 = 180°
statements
1. z1 is comp. to 22
2. z2 is comp. to 23
3. ?
4. mz1 - 90°-m22
5 m22+mz3 - 90°
6 m23 -90°-m22
7. mz1 =m23
reasons
1. given
2. given
3. def. of comp. zs
4. subtr. equality prop.
def. of comp. zs
6. subtr. equality prop.
7. trans, prop
and