Question

please answer only give correct answeres. don't give wrong answers​

Answer 1

Step-by-step explanation:

1 - cosB = (2/5) → cosB = (2/5) - 1

→ cosB = (3/5) = base/hypo.

Let, base be 3a and hypotenuse be 5a, using pythagoras theorem,

→ height² = (5a)² - (3a)² = 25a² - 9a²

→ height² = 16a² → height = 4a

Therefore, sinB = 4a/5a = 4/5

Solving LHS:

→ 25sinB(sinB - cosB)

→ 25(sin²B - sinB.cosB)

→ 25{(4/5)² - (3/5)(4/5)}

→ 25{ 16/25 - 12/25}

→ 25(16 - 12)/25

→ 25(4)/25

→ 4

Proved.