Question

b.
यदि 9 cosA+ 12 sinA = 15 है, तो cotA का मान ज्ञात करें।
(A) 3/4
(B) 12/13
(C) 1/3
(D) 35​

Answer 1

Answer:

we know that sin53°=3/5

and cos53°=4/5

now Divide by 15 both side in given question

9/15cosA + 12/15sinA = 1

3/5cosA + 4/5sinA =1

sin53°cosA + cos53°sinA =1

sin(53°+A) = 1. .•. sinAcosB + cosAsinB = sin(A+B)

sin(53°+A) = sin90°

comparing both side

53°+A = 90°

A=37°

Now

cotA =cosA/sinA

cotA=cos37°/sin37°

cotA=sin(90°-37°)/cos(90°-37°)

cotA=sin53°/cos53°

cotA=3/5×5/4

cotA=3/4

ans is cotA=3/4