#include <bits/stdc++.h>
using namespace std;
void solutionE();
int main() {
  ios_base::sync_with_stdio(false);
  solutionE();
  return EXIT_SUCCESS;
}
long long n;
long long v, T, x[100000], y[100000], r[100000];
pair<double, double> e[4 * 100000];
inline double dist(long long i) {
  return sqrt(((x[i]) * (x[i])) + ((y[i]) * (y[i])));
}
inline double dist(long long i, const double& alpha) {
  double hx = cos(alpha) * r[i];
  double hy = sin(alpha) * r[i];
  return sqrt(((hy) * (hy)) + ((dist(i) - hx) * (dist(i) - hx)));
}
const double PI = acos(-1.0);
const double PI2 = 2.0 * PI;
void solve() {
  cerr.precision(12);
  cout.precision(9);
  double D = T * v;
  long long ec = 0;
  for (long long i = 0; i < n; ++i) {
    double d = dist(i);
    if (x[i] * x[i] + y[i] * y[i] <= r[i] * r[i]) {
      cout << fixed << 1.0 << endl;
      return;
    }
    if (d - r[i] + 1e-9 > D) continue;
    double angle = atan2(y[i], x[i]), alpha = 0.0;
    if (angle < 0) angle += PI2;
    double R = acos(r[i] / d);
    if (dist(i, R) + 1e-9 < D) {
      if (fabs(R) < 1e-9)
        alpha = PI / 2.0;
      else
        alpha = atan(sin(R) * r[i] / (d - cos(R) * r[i]));
    } else {
      double xi = (((r[i]) * (r[i])) - ((D) * (D)) + ((d) * (d))) / (2.0 * d);
      R = acos((xi) / r[i]);
      if (fabs(R) < 1e-9) continue;
      alpha = atan(sin(R) * r[i] / (d - cos(R) * r[i]));
    }
    e[ec++] = make_pair(angle - alpha, angle + alpha);
    if (angle + alpha > PI2)
      e[ec++] = make_pair(angle - alpha - PI2, angle + alpha - PI2);
    if (angle - alpha < 0)
      e[ec++] = make_pair(angle - alpha + PI2, angle + alpha + PI2);
  }
  sort(e, e + ec);
  double last = 0.0;
  double total = 0.0;
  for (long long i = 0; i < ec; ++i) {
    auto& it = e[i];
    if (it.second - 1e-9 < last) continue;
    if (it.first + 1e-9 > PI2) continue;
    if (it.first - 1e-9 < last) {
      last = it.second;
    } else if (it.first + 1e-9 > last) {
      total += it.first - last;
      last = it.second;
    }
  }
  if (last < PI2) total += PI2 - last;
  cout << fixed << (PI2 - total) / (PI2) << endl;
}
void solutionE() {
  double x0, y0;
  for (; cin >> x0 >> y0 >> v >> T;) {
    cin >> n;
    for (long long i = 0; i < n; ++i) {
      cin >> x[i] >> y[i] >> r[i];
      x[i] -= x0;
      y[i] -= y0;
    }
    solve();
    break;
  }
}
