8. If a is a positive acute angle a...
Question
Fullscreen

8. If a is a positive acute angle and 2sina + 15cos'a = 7, then the value of cota is: polo

11th - 12th Class
Maths
Solution
142
Rating
4.0 (1 ratings)
Fullscreen
8. ( (1) 2 sin alpha+15 cos ^{2} alpha=7 ) ( Rightarrow 2 sin alpha+15left(1-sin ^{2} alpharight)=7 ) ( Rightarrow 2 sin alpha+15-15 sin ^{2} alpha=7 ) ( Rightarrow 15 sin ^{2} alpha-2 sin ^{2} alpha-8=0 ) ( Rightarrow 15 sin ^{2} alpha-12 sin alpha+10 sin ) ( alpha-8=0 ) ( Rightarrow 3 sin alpha(5 sin alpha-4)+2(5 ) ( sin alpha-4)=0 ) ( Rightarrow(3 sin alpha+2)(5 sin alpha-4)=0 ) ( Rightarrow 5 sin alpha-4=0 ) ( Rightarrow sin alpha=frac{4}{5} ) ( therefore operatorname{cosec} alpha=frac{5}{4} ) ( cot alpha=sqrt{operatorname{cosec}^{2} alpha-1} ) ( =sqrt{frac{25}{16}-1}=sqrt{frac{9}{16}}=frac{3}{4} )
Quick and Stepwise Solutions Just click and Send Download App OVER 20 LAKH QUESTIONS ANSWERED Download App for Free