The double angle formula for the sine is

The right hand side is exactly your expression, where 
So, rewriting the expression from right to left, we have

Answer:
<h3>
It's about 365 cm²</h3>
Step-by-step explanation:
2×πr² + 2πr×h =
= 2×π×4² + 2π×4×10.5 =
= 32π + 84π =
= 116π ≈
≈ 364.42 cm²
Answer:
1×3 or 3×3 I think...........
Answer:
a) no real solutions
Step-by-step explanation:
the discriminant (b² - 4ac) is negative which indicates no real solutions