Question

prove that sin(90degree - A) = cosA​

Answer 1

Answer:

You need to remember formula

sin(A+B)= sinA cos B + cosA sinB

put B= 90, A as -A

sin(90-A)= sin(-A) cos(90) + cos(-A) sin(90)

Remember cos90=0, sin90=1

So above expression becomes

sin(-A)×0 + cos(-A) (1)

= cos(-A)

= cosA

So , Proved

#answerwithquality #BAL

Answer 2

Answer:

sin(A+B)= sinA cos B + cosA sinB

put B= 90, A as -A

sin(90-A)= sin(-A) cos(90) + cos(-A) sin(90)

Remember cos90=0, sin90=1

So above expression becomes

sin(-A)×0 + cos(-A) (1)

= cos(-A)

= cosA

So , Proved