The ratio of DE to GH is 5:10, which simplifies to 1:2.

The sum of angles in a triangle is 180 degrees. Therefore, the third angle = 180 - (50 + 70) = 60 degrees.

The sum of the angles is 120 degrees, which means the third angle is 60 degrees. All angles are less than 90 degrees, so it is an acute triangle.

The area ratio is the square of the radius ratio. If area ratio = 1:4, then radius ratio = 1:2. Therefore, the radius of the second circle = 4 * 2 = 8 cm.

The ratio of the sides of the two similar triangles is 5:15, which simplifies to 1:3.

If the ratio is 2:3, then the sides of the second triangle are (3 * 3/2), (4 * 3/2), (5 * 3/2) = 4.5, 6, 7.5. The closest whole numbers are 6, 8, 10.

Using the distance formula, d = √((x2 - x1)² + (y2 - y1)²) = √((7 - 3)² + (1 - 4)²) = √(16 + 9) = √25 = 5.

Since two angles are equal, triangle GHI is an isosceles triangle.

Using the Pythagorean theorem, 8² + 6² = 64 + 36 = 100 = 10², so triangle JKL is a right triangle.