Question

Without using trignometric tables, evaluate (3 cos 43/sin 47)2 - cos 37 cosec 53/ tan5 tan25 tan45 tan65 tan 85

Answer 1

we know sin A = cos (90-A)            cosec A = sec(90-A)

Numerator :  
  (3 cos 43 / sin 47)² - cos 37 Cosec 53 
 = (3 cos 43 / cos43)² - cos 37 sec (37)
 = 3² - 1 = 8

we know  tan A = cot (90-A) = 1/tan(90-A).  Apply this for denominator.

Denominator :
 = tan 5  tan85 tan 45 tan 25  tan 65
 = tan 5 * 1/tan5  * tan 45 * tan 25 * 1/tan25
 = 1          as tan 45 = 1

Answer = 8

Answer 2

Answer:

hopefully this answer helps u