Sкруга = πR² = π·1 = π
Sсект = πr²·α/360°
π·4·α/360° = π
α/90° = 1
α = 90°
<span>cos a- cos3a + 2 sin 2a=-2sin(2a)*cos(-a)+2 sin 2a=2 sin 2a(1-cos(a))</span>
<span>2<span>a^3</span>+<span>a^2</span>−1−3<span>a^2</span>+<span>a^3</span>−a=</span><span>3<span>a^3</span>−2<span>a^2</span>−1−a=</span><span><span>3<span>a^3</span>−2<span>a^2</span>−a−1</span></span>
-2x²+5x-1+3x²+5x-3= x²+10x-4
-2x²+5x-1-3x²-5x+3= -5x²+2
(-2x²+5x-1)*(3x²+5x-3)= -6x⁴-10x³+6x²+15x³+25x²-15x-3x²-5x+3= -6x⁴+5x³+28x²-20x+3