contestada

PLS HELP URGENT

In triangle PQR.
Sis the point on PR such that angle RSQ = 90°
RQ = 14 cm
RS -- 10 cm
SP - 5 cm
Work out the length of PQ.

PLS HELP URGENT In triangle PQR Sis the point on PR such that angle RSQ 90 RQ 14 cm RS 10 cm SP 5 cm Work out the length of PQ class=

Respuesta :

hoaiilinhh12

PQ=11

PS^2+SR^2=QR^2

PS^2+PS^2=PQ^2

sqdancefan

9514 1404 393

Answer:

  11 cm

Step-by-step explanation:

The law of cosines can be helpful here. In order to find PQ, we must know the cosine of the angle R. Fortunately, SOH CAH TOA reminds us it is ...

  Cos = Adjacent/Hypotenuse

  cos(R) = 10/14 = 5/7

__

The law of cosines gives us the relation ...

  PQ^2 = PR^2 +QR^2 -2·PR·QR·cos(R)

  PQ^2 = 15^2 +14^2 -2(15)(14)(5/7) = 121

  PQ = √121 = 11

The length of PQ is 11 cm.

_____

Alternate solution

This can be solved using the Pythagorean theorem twice.

  QS^2 = QR^2 -SR^2 = 14^2 -10^2 = 96

  PQ^2 = PS^2 +QS^2 = 5^2 +96 = 121

  PQ = √121 = 11

Otras preguntas