`T a n 58 5^(@)C o t 40 5^(@)+T a n 67 5^(@)C o t 76 5^0=`

An object at temperature 70^(@)C is placed in a surrounding medium of temperature 30^(@)C . Its temperature decreases by 10^(@)C in first 5 min. Find the time interval from starting in which its temperature reduces to 40^(@)C . Assume Newton's law to be valid. t = 0 " "T = 70^(@)C" "T_("env") = 30^(@)C t = 5 " "T = 60^(@)C" "T_("env") = 30^(@)C time = t T = 40^(@)" " T_("env") = 30^(@)C

If A+B+C=180^0 , then (t a n A+t a n B+t a n C)/(t a n A t a n B t a n C) is equal to t a n A t a n B t a n C b. 0 c. 1 d. none of these

Show that : (i) t a n" "48o" "t a n" "23o" "t a n" "42o" "t a n" "67o" "=" "1(i i) cos" "38o" "cos" "52o" "" "s in" "38o" "s in" "52o" "=" "0

If A+B+C=180^0 , then (t a n A+t a n B+t a n C)/(t a n A\ t a n B\ t a n C) is equal to a. t a n A t a n B t a n C b. 0 c. 1 d. none of these

Prove that: \ t a n 20^0t a n 30^0t a n 40^0t a n 80^0=1

If n ( C cup T ) = 70, n ( C ) = 37 and n ( T ) = 35 . Then, n ( C cap T) is equal to

In triangle A B C , if sinAcosB=1/4a n d3t a n A=t a n B ,t h e ncot^2A is equal to 2 (b) 3 (c) 4 (d) 5.

If 5t - 3 = 3t - 5 , then t =?