` z = cos 70^@ + i cos 20 ^@ = cos 70 ^@ + i cos (90 ^@ – 70 ^@ ) `
` = cos 70 ^@ + i sin 70 ^@ `
` = cos “” ( 70 pi )/ ( 180 ) + i sin “” ( 70 pi ) /( 180 ) + i sin “” ( 70 pi ) / ( 180) = 1 . ( cos “” ( 7pi ) /( 18) + i sin “” ( 7pi ) /(18)) `
` therefore |z| = 1 ` तथा arg z का मुख्य मान = ` 7pi // 18 ” ” [ because 7 pi//18 in ( – pi, pi ) ] `

` z = ( 5 ) / ( 2 ) ( cos 300^ @ + i sin 30 ^@ ) = ( 5 ) /(2) ( cos ( 360 ^@ – 60 ^@ ) + i. ( 1 ) / ( 2 ) ) `
` = ( 5 ) /(2) ( cos 60 ^@ + i. ( 1 ) / ( 2 ) ) `
` = ( 5 ) / ( 2 ) ( ( 1 ) / (2 ) + i . ( 1 ) / (2 ) ) = ( 5 ) / ( 2 sqrt2 ) (( 1 ) /( sqrt 2 ) + i. ( 1 ) / ( sqrt 2 ) ) `
` = ( 5 ) /( 2sqrt 2 ) ( cos “” ( pi ) / ( 4 ) + i sin “” ( pi ) / ( 4 )) `
` therefore |z| = ( 5 ) / ( 2sqrt 2 ) ` तथा arg z कोणाक का मुख्य मान ` z = ( pi ) /( 4 ) ( because ( pi ) / ( 4 ) in ( – pi , pi ) ) `