Question

Find the missing side or angle.Round to the nearest tenth.b=15a=30c=29A=[ ? 1°

Answer 1

STEP 1

The given parameters are a=30, b=15 and c=29

The corresponding cosine rule needed to find the angle A is denoted below

$A=\cos ^{-1}\mleft[\frac{b^2+c^2-a^2}{2bc}\mright]^{}$

STEP 2

Substitute the given parameters into the equation.

$\begin{gathered} A=\cos ^{-1}\mleft\lbrace\frac{15^2+29^2-30^2}{2\times15\times29}\mright\rbrace \\ A=\cos ^{-1}\mleft\lbrace\frac{225+841-900}{870}\mright\rbrace \\ A=\cos ^{-1}\mleft\lbrace\frac{166}{870}\mright\rbrace \\ A=\cos ^{-1}0.1908 \\ A=79.0^0 \end{gathered}$