Answer:
[tex]x=30[/tex]
Step-by-step explanation:
For each right-angled triangle:
[tex]\cos\theta=\frac{cathetus \ adjacent \ \theta}{hypotenuse}[/tex]
Because [tex]\cos \theta=0.4, \ \ cathetus\ adjacent \ \theta \ = \ 12, \ \ \ hypotenuse=x[/tex]
we have an equation
[tex]0.4=\frac{12}x[/tex]
multiplying both sides by x, we get [tex]0.4x=12[/tex]
dividing both sides by 0.4 and [tex]x=\frac{12}{0.4}[/tex]
using calculator, we divide 12 by 0.4
and finally x=30
