This is an isosceles triangle since the two sides adjacent to the x angle are the same length. The angle opposite the 110 is 70 since these are supplementary angles. Angle y is 70 (isosceles triangle has two sides equal and two angles equal). The sum of the interior angles of a triangle is 180, so x = 180 - 70 - 70 = 40.
We know that applying the law of cosines a² = b²+ c²<span> – 2*b*c*cos(A) cos (A)=[b</span>²+c²-a²]/[2*b*c] in this problem a=10 b=17 c=18 so cos (A)=[17²+18²-10²]/[2*17*18]-----> cos (A)=0.8382 A=arc cos (0.8382)-----> A=33.05°-----> A=33°
