the length of each side of the ABCD EFGH cube is 6cm. If point P is located in the middle of line EH, point Q is in the middle of line EF, and point R is in the middle of line AE, determine the distance of point E to the PQR plane

Respuesta :

Answer:

           The distance is:   [tex]\sqrt3\ cm\approx1,73\,cm[/tex]

Step-by-step explanation:

The distance of point E to the PQR plane it is the hight (vertical) of piramid PRQE

If point P is located in the middle of line EH, point Q is in the middle of line EF, and point R is in the middle of line AE than:

EP = EQ = ER = 0.5EF = 3 cm  and  m∠REQ = m∠QEP = m∠REP = 90° so triangles RQE, QPE and PRE are congruent.

RQ = QP = PR so triangle PQR is equilateral and from Pythagorean theorem (for ΔRQE):

[tex]RQ^2=ER^2+EQ^2=3^2+3^2=2\cdot3^2\ \ \implies\ \ RQ=3\sqrt2[/tex]

Then: [tex]RN=\dfrac{RQ\,\sqrt3}2[/tex]

and:  [tex]RK=\dfrac23RN=\dfrac{RQ\,\sqrt3}3=\dfrac{3\sqrt2\cdot\,\sqrt3}3=\sqrt6[/tex]

Therefore from Pythagorean theorem (for ΔERK):

[tex]EK^2+RK^2=ER^2\\\\EK^2=ER^2-RK^2\\\\EK^2=3^2-(\sqrt6)^2\\\\EK^2=9-6=3\\\\EK=\sqrt3\ cm\approx1,73\,cm[/tex]

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