Question

Cos ^20 + cos^ 70 + cot 25/tan65 +cot 5cot 10cot 60cot 80cot 85 , whose ans is 6+√3/3

Answer 1

Answer:

Step-by-step explanation:

(Cos^2 20+ cos^2 70)+cot25/tan65+cot5cot10cot60cot80cot85 We have identity Cos(90-a)=sin a tan(90-a)= cota ={Cos^2(90-20)+cos^2 70}+{cot(90-65)/tan 65)}+cot(90-85)cot(90-80)cot60 cot80 cot85} =(Sin^2 70+cos^2 70) + tan 65/tan65+ (tan85 tan. 80 cot60 cot 80 cot85) =1+1+ 1×√3×1 = 2+√3