a)Ta có:
$\widehat{yOz} $ + $\widehat {xOz}$= $\widehat {xOy}$
⇒ $60^{o}$ + $\widehat {xOz}$ = $180^{o}$
⇒ $\widehat {xOz}$ = $180^{o}$ - $60^{o}$
⇒ $\widehat {xOz}$ = $120^{o}$
b) Ta có:
$\widehat {mOz}$ = `1/2` $\widehat {xOz}$
⇒ $\widehat {mOz}$ = `1/2` · $120^{o}$
⇒ $\widehat {mOz}$ = $60^{o}$
Ta có: $\widehat {zOn}$ = `1/2` $\widehat {yOz}$
⇒ $\widehat {zOn}$ = `1/2` · $60^{o}$
⇒$\widehat {zOn}$ = $30^{o}$
Ta có: $\widehat {mOz}$ + $\widehat {zOn}$ = $\widehat {mOn}$
⇒ $60^{o}$ + $30^{o}$ = $\widehat {mOn}$
⇒$\widehat {mOn}$ = $90^{o}$
Vậy $\widehat {mOz}$ = $60^{o}$
$\widehat {zOn}$ = $30^{o}$
$\widehat {mOn}$ = $90^{o}$
c) Không là 2 góc phụ nhau vì nó không nằm chung trên 1 mặt phẳng