if 1-cos b = 2/5 , prove that 25 sin b [ sin b - cos b ] = 4
 

1-cosb =2/5 cosb =1-2/5 cosb=3/5 sin²b =1-cos²b =1-9/25 = 16/25 sinb= 4/5 25sinb(sinb-cosb) =25 ×4/5 × (4/5-3/5) =5×4×1/5 =4

  • 2
What are you looking for?