Question

If a,b are complementary angles , sina=3/5, then cosacosb-sinasinb=

Answer 1

Step-by-step explanation:

cos a = 2 / 5

cosb = 3 /5

sinb = 1 as b = 90

cosacosb - sina sinb

2/5 × 3/5 - 3/5 ×1

6/5 - 3/5

=3/5

Answer 2

Answer:

Step-by-step explanation:

as the angles are complementary

a+b=90

given

sina=3/5

cosa=4/5 as sin square a +cos square a is one

sinb =sin(90-a)=cosa=4/5

cosb=cos(90-a)=sina=3/5

then we get

cosacosb-sinasinb=4/5*3/5-3/5*4/5

=12/5-12/5=0

hence zero is answer