Given a integer depending on whether or not it is positive or negative it is always opposite of what it is. For example the opposite of 7 is -7
I think that you are mistaking the memory tool for something else
or a math book is trying to make math cute by calling them 'socatoa joe' and 'mr. pi' and such
anyway, SOH, CAH, TOA is the way to remember
Sine=oposite/hypotonuse
Cosine=adjacent/hypotonuse
Tangent=oposite/adjacent
(oposite side=side oposite the angle
adjacent is the side touching the angle that is not they hypotonuse
and of course the hypotonuse is the longest side aka, side oposite right angle)
Because there are only two things you can do with these two " family" members. 81 divided by 9 is 9. 9 times 9 is 81. Strictly speaking, there should be three in the family: 9,9 and 81 9 is the square root of 81. 81 is the 9 squared.
The area bounded by the 2 parabolas is A(θ) = 1/2∫(r₂²- r₁²).dθ between limits θ = a,b...
<span>the limits are solution to 3cosθ = 1+cosθ the points of intersection of curves. </span>
<span>2cosθ = 1 => θ = ±π/3 </span>
<span>A(θ) = 1/2∫(r₂²- r₁²).dθ = 1/2∫(3cosθ)² - (1+cosθ)².dθ </span>
<span>= 1/2∫(3cosθ)².dθ - 1/2∫(1+cosθ)².dθ </span>
<span>= 9/8[2θ + sin(2θ)] - 1/8[6θ + 8sinθ +sin(2θ)] .. </span>
<span>.............where I have used ∫(cosθ)².dθ=1/4[2θ + sin(2θ)] </span>
<span>= 3θ/2 +sin(2θ) - sin(θ) </span>
<span>Area = A(π/3) - A(-π/3) </span>
<span>= 3π/6 + sin(2π/3) -sin(π/3) - (-3π/6) - sin(-2π/3) + sin(-π/3) </span>
<span>= π.</span>
