Question

can any one prove this plz
trigonometric sums 10 th std​

Answer 1

Answer:

Step-by-step explanation:

(Cos70 / sin20 )+ ((cos55 cosec35 )/ (tan5 tan25 tan45 tan65 tan85))

=(cos(90-20) /sin20)+(cos55 cosec35)/(tan5 tan25 tan45 tan(90-25) tan(90-5))

= (sin20/ sin20) + (cos55 cosec35)/ (tan5 tan25 tan45 cot25 cot5)

= 1+ (cos55 cosec35)/(1)

= 1+ (cos55/sin35)

= 1+(sin(90-35)/sin35)

= 1+(sin35/sin35)

= 1+1

= 2

Answer 2

Hello user !

Solution:-

Firstly , Some complementary dearivations to be seen.

sin (90 -A)°= cosA°

tan(90-A)°= cotA°

Now in the given question:

=cos70°/sin20 °+. ( cos 55°*cosec 35° )/(tan5°*tan25°*tan65°*tan85°)

=cos (90-20)°/sin 20° + ( cos( 90 - 35) °*cosec35)° / (tan (90 -5)°*tan 5° *tan (90-65)°* tan 65)°

=sin 20° /sin20° + sin 35° * cosec 35° /(cot5°*tan 5° * tan 65°* cot 65°)

{sin A°* cosec A° =1}

=1+. 1/ (1*1)

=1+1

=2 i.e R.H.S

Hope it helps ❤ ❤