Question

What is the value of s to the nearest whole number? a) 13 b) 12 c) 14 d) 10

Answer 1

Given:

In given Δ RST,

RS = 9, ST = 8 and ∠S = 110°

To find the value of another side RT (s).

Formula

By cosine law we get,

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

Now,

Putting,

b=9, c=8, A = 110° and a=s we get,

$s^{2}=9^{2} +8^{2} -2(9)(8)(cos110^\circ)$

or, $s^{2} =81+64-2(9)(8)(-0.342)$

or, $s^{2}= 194.248$

or, $s = \sqrt{194.248}$

or, $s = 13.93$

or, $s=14$

Hence,

The value of s is 14. Option C.