Question

if 1-cos B=2/5,prove that 25 sinB(sin B- cosB)=4

Answer 1

Step-by-step explanation:

1-CosB = 2/5

CosB = 3/5 then SinB = 4/5

25 × 4/5 ( 4/5 - 3/5 ) = 4

20 ( 1/5) = 4

4 = 4

LHS = RHS

Hence Proved