Matlab functions

computations with built in functions $($elementary functions$)[4]$

a$)$ find the value of $b=si{n}^{\text{'}}1(0\mathrm{.}7071)$ in degrees using matlab functions

b$)$ write a program to calculate the hyperbolic cosine of a user$-$defined value $x$; hence determine the value of hyperbolic cosine $(3,2)$

c$)$ find the solutions to the following linear equations

$2x_1+2x_2+3x_3=1$

$4x_1+5x_2+6x_3=2$

$7x_1+8x_2+9x_3=3$