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Given the following expressions:

[tex]\[ \cos (\theta) \quad \sin (\theta) \quad 59^{\circ} \quad 62^{\circ} \quad 90+33 \quad 90+\theta \quad 57^{\circ} \quad 90-\theta \][/tex]

Complete the identities:

[tex]\[
\begin{array}{l}
\sin \left(28^{\circ}\right)=\cos ( \\
\cos \left(33^{\circ}\right)=\sin ( \\
\cos \left(31^{\circ}\right)=\sin ( \\
\cos (90-\theta)=
\end{array}
\][/tex]


Sagot :

Let's solve each part of the question step-by-step:

### 1. [tex]\(\sin(28^\circ)\)[/tex]
We are asked to find a relation involving [tex]\(\sin(28^\circ)\)[/tex]. Recall that:
[tex]\[ \sin(x) = \cos(90^\circ - x) \][/tex]
Thus:
[tex]\[ \sin(28^\circ) = \cos(62^\circ) \][/tex]
The numerical value is:
[tex]\[ \sin(28^\circ) \approx 0.46947156278589086 \][/tex]

### 2. [tex]\(\cos(33^\circ)\)[/tex]
Similarly, for this part, we need to recall that:
[tex]\[ \cos(x) = \sin(90^\circ - x) \][/tex]
Therefore:
[tex]\[ \cos(33^\circ) = \sin(57^\circ) \][/tex]
The numerical value is:
[tex]\[ \cos(33^\circ) \approx 0.838670567945424 \][/tex]

### 3. [tex]\(\cos(31^\circ)\)[/tex]
Using the same identity:
[tex]\[ \cos(31^\circ) = \sin(59^\circ) \][/tex]
The numerical value is:
[tex]\[ \cos(31^\circ) \approx 0.8571673007021123 \][/tex]

### 4. [tex]\(\cos(90^\circ - \theta)\)[/tex]
For the final part, we apply the identity directly concerning [tex]\(\theta\)[/tex]:
[tex]\[ \cos(90^\circ - \theta) = \sin(\theta) \][/tex]

By rewriting each part, our final results are:

[tex]\[ \begin{array}{l} \sin (28^\circ)=\cos (62^\circ) \approx 0.46947156278589086, \\ \cos (33^\circ)=\sin (57^\circ) \approx 0.838670567945424, \\ \cos (31^\circ)=\sin (59^\circ) \approx 0.8571673007021123, \\ \cos (90^\circ-\theta)=\sin (\theta) \end{array} \][/tex]

This completes our solution for each requested trigonometric relation.