Section- D ( 4 marks for each ) 16 For given, To prove, construction and figure and for correct proof 2+2 17 Sn= 4n-n2 S1 = 4x1 -12 =3 1 a1= S1=3 S2 = 4x2-22 = 8-4 =4 1 a2 = S2 S1= 4-3 =1 – d= a2 a1= 1-3 = -2 1 – an = a+(n-1)d= 3+ (n-1)(-2) =5-2n 1 18 D C 1 B In figure, BC represent height of building and CD represent height of tower. BC = 20 m CD = h 1 BAC = 450 and BAD =600 In ,tan 45 =BC/AB 1= 20/BC 1 BC=20 In , tan 60 = DB/AB =(20 +h)/20 1
Section- D ( 4 marks for each ) 16 For given, To prove, construction and figure and for correct proof 2+2 17 Sn= 4n-n2 S1 = 4x1 -12 =3 a1= S1=3 S2 = 4x2-22 = 8-4 =4 a2 = S2 – S1= 4-3 =1 d= a2 – a1= 1-3 = -2 an = a+(n-1)d= 3+ (n-1)(-2) =5-2n 1 1 1 1 18 D C B In figure, BC represent height of building and CD represent height of tower. BC = 20 m CD = h BAC = 450 and BAD =600 In ,tan 45 =BC/AB 1= 20/BC BC=20 In , tan 60 = DB/AB =(20 +h)/20 1 1 1 1