Question

The law of cosines for RST can be set up as 52 = 72 + 32 – 2(7)(3)cos(S). What could be true about RST?

Answer 1

The correct answer is D.

Answer 2

we know that

the law of cosines is equal to

$a^{2} =b^{2} +c^{2}-2(b)(c)cos(A)$

In this problem  for the triangle RST

we have

$5^{2} =7^{2} +3^{2}-2(7)(3)cos(S)$

so

$s=5$

$r=7$ or $r=3$

$t=3$ or $t=7$

the possibilities are

1) $s=5$

  $r=7$

  $t=3$

2) $s=5$

  $r=3$

  $t=5$

therefore

the answer is the option

s = 5 and t = 3