The base of the ladder in the figure is a=7 ft from the building, and the angle formed by the ladder and the ground is 69°. How high up the building does ladder touch. (Round your answers to one decimal point.)

Step 1 ：We are given a right triangle where the base of the ladder is 7 ft from the building, forming an angle of 69° with the ground. We are asked to find the height up the building where the ladder touches.

Step 2 ：We can use the sine function to solve this problem. The sine of an angle in a right triangle is defined as the length of the opposite side divided by the length of the hypotenuse.

Step 3 ：In this case, we know the length of the adjacent side (a=7 ft) and the angle (69°). We want to find the length of the opposite side (height of the building where the ladder touches).

Step 4 ：We can rearrange the sine function to solve for the opposite side: \( \sin(69°) = \frac{opposite}{hypotenuse} \). We can rearrange this to find the opposite side: \( opposite = \sin(69°) \times hypotenuse \).

Step 5 ：Substituting the given values, we get \( opposite = \sin(69°) \times 7 \).

Step 6 ：Calculating the above expression, we get the height as 18.235623452856604 ft.

Step 7 ：Rounding off the above value to one decimal point, we get the height as 18.2 ft.

Step 8 ：Final Answer: The ladder touches the building at a height of \( \boxed{18.2} \) feet.