Question

Find the length of the line PA.

Answer 1

RO divides the rectangle into two congruent right triangles.

The area of the one triangle is equal half area of the rectangle.

Calculate the area of rectangle:

$A_R=lw\\l=12,\ w=5\\\\A_R=12\cdot5=60$

The area of right triangle:

$A_T=\dfrac{1}{2}A_R\to A_T=\dfrac{1}{2}\cdot60=30$

Use the Pythagorean theorem to calculate the length of RO:

$|RO|^2=5^2+12^2\\\\|RO|^2=25+144\\\\|RO|^2=169\to|RO|=\sqrt{169}\to|RO|=13$

The formula of an area of this right triangle is:

$A_T=\dfrac{1}{2}|RO||PA|$

Therefore we have the equation:

$\dfrac{1}{2}(13)|PA|=30\qquad|\cdot2\\\\13|PA|=60\quad|:13\\\\|PA|=\dfrac{60}{13}\\\\|PA|\approx4.62$