no 45 caranya gimana bingung...?

1. tan A (cot A - cos A)
= (sin A/cos A) (cos A/sin A - cos A)
= 1 - sin A (benar)
2. (sin A + cos A) (sin A - cos A)
= sin²A - cos²A
= 1 - cos²A - cos²A
= 1 - 2cos²A
3. (sin A + cos A)²
= sin²A + cos²A + 2sin A cos A
= 1 + 2 sin A cos A (salah)
4. sin A cos A / tan A
= sin A cos A / (sin A/cos A)
= sin A cos A × (cos A/sin A)
= cos²A (benar)