Question Number 100815 by john santu last updated on 28/Jun/20

Answered by mr W last updated on 28/Jun/20

see Q47657    δ=(2+3+(√7))(−2+3+(√7))(2−3+(√7))(2+3−(√7))  =108  side length of equilateral triangle:  l=(√((2^2 +3^2 +((√7))^2 +(√(3×108)))/2))=(√((20+18)/2))=(√(19))  cos α=((19+4−7)/(2×(√(19))×2))=((4(√(19)))/(19))  ⇒tan α=((√3)/4)  cos β=((19+9−7)/(2×(√(19))×3))=((7(√(19)))/(38))  ⇒tan β=((3(√3))/7)  tan (α+β)=((tan α+tan β)/(1−tan α tan β))  =((((√3)/4)+((3(√3))/7))/(1−((√3)/4)×((3(√3))/7)))=(√3)  ⇒Answer A

Commented bybramlex last updated on 29/Jun/20

what is δ sir?

Commented bymr W last updated on 29/Jun/20

see formula in Q47657

Commented bymr W last updated on 29/Jun/20