Please do not double post ..

(1) $\displaystyle cos\theta=0.3842$

$\displaystyle cos^{-1}0.3842=....$

(2) Given that $\displaystyle cos\theta=0.7$ , the 5 other trigo function are sin , tan , cot, cosec,and sec .

Just draw a triangle ..

More about your calculator

For question 1 work out: $\displaystyle cos^{-1}0.3842=\theta$

You mentioned your calculator wasn't working properly. Are you sure you have it on the degrees setting? Because if it's set on radians you'll get an answer of 1.17646, and if it's on grads you'll get 74.89546.

If you still can't get it to work properly, Windows have a program called calculator under accessories.