The sum of three internal angles in any triangle is always 180°
For the given triangle:
Internal angles: 90°, 7x, 8x
[tex]90+7x+8x=180[/tex]
You use the equation above to find the value of x:
[tex]\begin{gathered} 90+15x=180 \\ 15x=180-90 \\ 15x=90 \\ x=\frac{90}{15} \\ \\ x=6 \end{gathered}[/tex]
As the value of the x is 6 you can find the measure of the acute angles:
[tex]\begin{gathered} 7x=7(6)=42 \\ \\ 8x=8(6)=48 \end{gathered}[/tex]
Acute angles are: 8x=48° and 7x=42°
