Question

Calculate the largest size of the calculator

Answer 1

well, the largest angle will have the longest side too, so that means the angle "C", hmmm so let's use the Law of Cosines for that

`\textit{Law of Cosines}\\\\ \cfrac{a^2+b^2-c^2}{2ab}=\cos(C)\implies \cos^(-1)\left(\cfrac{a^2+b^2-c^2}{2ab}\right)=\measuredangle C \\\\[-0.35em] ~\dotfill\\\\ \cos^(-1)\left(\cfrac{11^2+7^2-15^2}{2(11)(7)}\right)=\measuredangle C \implies \cos^(-1)\left(\cfrac{ -55 }{ 154}\right)=\measuredangle C\implies 110.92^o\approx\measuredangle C`

Make sure your calculator is in Degree mode.