Here is an example of a TypeScript class that can be used to check if a given latitude and longitude point is within a specified radius:

```
class LatLonRadiusChecker {
private radius: number;
constructor(radius: number) {
this.radius = radius;
}
public isInRadius(lat: number, lon: number, centerLat: number, centerLon: number): boolean {
// convert lat/lon to radians
lat = lat * (Math.PI / 180);
lon = lon * (Math.PI / 180);
centerLat = centerLat * (Math.PI / 180);
centerLon = centerLon * (Math.PI / 180);
// calculate deltas
const deltaLat = lat - centerLat;
const deltaLon = lon - centerLon;
// calculate the haversine formula
const a = Math.sin(deltaLat / 2) * Math.sin(deltaLat / 2) +
Math.cos(centerLat) * Math.cos(lat) *
Math.sin(deltaLon / 2) * Math.sin(deltaLon / 2);
const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
// calculate the distance in kilometers
const distance = 6371 * c;
return distance <= this.radius; } < code>
```To use this class, you would first need to create an instance of it, passing in the radius in kilometers that you want to use for the check:

`const checker = new LatLonRadiusChecker(50); // radius of 50 km>`

You can then use the `isInRadius()`

method to check if a given latitude and longitude point is within the specified radius:

```
const isInRadius = checker.isInRadius(40.7127, -74.0059, 39.9042, 116.4074);
// New York City and Beijing
// isInRadius is false
```

Note that the `isInRadius()`

method expects the latitude and longitude values to be in decimal degrees. If you have the values in another format, you will need to convert them before using the method.