kak yang no 43 gimana ya tolong bantu dong

1/cos 75 + 1/cos 15

= (cos 15 + cos 75) /(cos 75. cos 15) 
= { 2 cos 1/2 (75+15) cos 1/2 (75-15)} / (1/2 (2 cos 75 cos 15 ))
= ( 2cos 45 cos 30 )/  1/2 (cos (75+15)+ cos (75-15)}
= (2. 1/2√2. 1/2 √3 ) / 1/2 (cos 90 + cos 60)
= (1/2 √6 )/ (1/2(0+1/2)
= (1/2 √6)/(1/4)
= 4 (1/2) √6
= 2 √6