Chapter 13.2, Problem 23WE

To determine

To Verify: The identity ${\cos }^{2}s+{\sin }^{2}s=1$ if $s=0.7$.

Answer to Problem 23WE

The given identity is verified.

Explanation of Solution

Given information:

The given information is ${\cos }^{2}s+{\sin }^{2}s=1$ if $s=0.7$ .

Calculation:

Use a calculator to verify the identity. Set the calculator in radian mode.

Press the key $\sin$ , and insert the number $0.7$ .The display will be about $0.6442$ .

Press the key $\cos$ , and insert the number $0.7$ .The display will be about $0.7648$ .

Substitute $0.6442$ for $sins$ , and $0.7648$ for $\cos$ in ${\cos }^{2}s+{\sin }^{2}s=1$ , and verify.

  $\begin{array}{l}{\left(0.7648\right)}^2+{\left(0.6442\right)}^2=1\\ 0.5850+0.4150\approx 1\end{array}$

Therefore, the given identity is verified.