let's call it's initial elevation x. because it descends 3 miles, we now have x - 3. the question says it is now 15 miles above sea level, or x - 3 = 15, and adding 3 to both sides shows that x = 18 miles.
step-by-step explanation: first, on the right side you subtract (90-114) - (66). the answer will be -90. then, you set the equation up as s+24=-90. to get s by itself, subtract 24 from both sides. it should look like this s+24-(24)=-90-(24). once you know that -90-24=-114, your new equation will be s=-114. therefore, the value of s is -114. if you need reassurance, you can add 24 to -114, which gives you -90.
triangle b is right
using the converse theorem of pythagoras.
if the square of the longest side in a triangle equals the sum of the squares of the other 2 sides then the triangle is right.
longest side squared = 36² = 1296
26² + 18² = 676 + 324 = 1000 ≠ 1296
hence triangle a is not right
longest side squared = 25² = 625
20² + 15² = 400 + 225 = 625 ← correct
hence triangle b is right
where is the shape my dude?