Xét Tam giác `MPQ` có:
\(\widehat{M}+\widehat{MPQ}+\widehat{MQP}=180^0\) (đli tổng 2 góc trong 1 Tam giác)
\(50^0+\widehat{MPQ}+90^0=180^0\)
`=>` \(\widehat{MPQ}=40^0\)
\(\widehat{MQP}+\widehat{NQP}=180^0\) (kề bù)
\(90^0+\widehat{NQP}=180^0\)
`=>` \(\widehat{NQP}=90^0\)
Xét Tam giác `NPQ` có:
\(\widehat{N}+\widehat{NQP}+\widehat{NPQ}=180^0\)
\(40^0+90^0+\widehat{NPQ}=180^0\)
`=>` \(\widehat{NPQ}=50^0\)