Wash the cucumbers thoroughly under cold water.
Slice cucumbers thinly, about 1/4 inch thick.
In a mixing bowl, combine yogurt, mayonnaise, vinegar, sugar, and garlic powder.
Mix the dressing until smooth and well combined.
Add salt and pepper to taste.
Combine the sliced cucumbers and the dressing in a large bowl.
Toss the cucumbers to coat them evenly with the dressing.
Cover and refrigerate the salad for at least 30 minutes.