MaxWong

$\dfrac{1}{8}=12.5\%$

So $8\dfrac{3}{8}=8+\dfrac{1}{8}\times 3=800\% + 12.5\%\times 3=837.5\%$

Yes. Definitely there is some trick.

Remember that $i^2=-1$,

so $i^4=i^2\cdot i^2=-1\cdot -1=1$

Therefore $i^{4n}=(i^4)^n=1^n=1$, for any integer n.

$i^8=(i^4)^2=1^2=1$

$i^{25}=i^{24}\times i=(i^4)^6\times i=1\times i = i$

$\cos^{-1}$ this one?

it is same as "acos".

$v=\dfrac{1}{4}\pi d^2z\\ 4v= \pi d^2z\\ d^2=\dfrac{4v}{\pi z}$

$\because x^3=20x+7y\text{ and }y^3=7x+20y\\ \therefore x^3-y^3=(x-y)(x^2+xy+y^2)=13x-13y\\ x^2+xy+y^2 = 13\\ x^3+y^3 =(x+y)(x^2-xy+y^2)=27(x+y)\\ x^2-xy+y^2=27\\ (x^2+xy+y^2)-(x^2-xy+y^2)=-14\\ xy = -7$

https://www.desmos.com/calculator/kx7nzzw1bj --- sector

https://www.desmos.com/calculator/pk1qw7oc44 --- spiral

https://www.desmos.com/calculator/m6khfpqpq9 --- wiggle wiggle wiggle XD

https://www.desmos.com/calculator/qnbd93wkqu --- infinity sign

I created them all :D

https://www.desmos.com/calculator/wp747grseh

I feel stupid by creating this thing XD

Dividing by a number means multiplying the reciprocal of the number.

So 1/2 divided by 7 = 1/2 x 1/7 = 1/(2x7) = 1/14

Because △ABC is similar to △DEF, angle ABC should equal 60 deg as well. 

$\boxed{ \text{The sum of all interior angles of a triangle is 180}^{\circ}}$

So Angle C = 180 - 55 - 60 = 65 deg :D

Do you mean 125 in cubed instead?

Then side length = $\sqrt[3]{125}$ which is 5 in.