#include <bits/stdc++.h>
using namespace std;
const double Pi = 3.14159265358979323;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie();
  double x0, y0, v, T, n, x, y, r;
  vector<tuple<double, double> > c;
  cin >> x0 >> y0 >> v >> T;
  T = v * T * 1.0;
  cin >> n;
  while (n--) {
    cin >> x >> y >> r;
    double angulo, d, adiff;
    d = sqrt((x - x0) * (x - x0) + (y - y0) * (y - y0));
    if (d * d <= r * r || (x == x0 && y == y0)) {
      cout << "1.000\n";
      return 0;
    }
    if (r == 0) continue;
    if (d * d >= ((r + T) * (r + T))) continue;
    angulo = atan2(y - y0, x - x0);
    if (angulo < 0) {
      angulo += 2 * Pi;
    }
    if (sqrt(d * d - r * r) <= T) {
      adiff = asin(r / d);
    } else {
      adiff = acos((-r * r + T * T + d * d) / (2 * T * d));
    }
    double x1 = angulo - adiff;
    if (x1 < 0) x1 = 2 * Pi + x1;
    c.push_back(make_tuple(x1, 1));
    x1 = angulo + adiff;
    if (x1 > 2 * Pi) x1 -= 2 * Pi;
    c.push_back(make_tuple(x1, -1));
  }
  sort(c.begin(), c.end());
  double s = 0.0;
  int in = 0, fin = -1;
  vector<int> sweep(c.size(), 0);
  while (in != fin && c.size() != 0) {
    double angulo, con;
    if (fin == -1 && in == 0) fin = 0;
    tie(angulo, con) = c[in];
    if (con == -1 && s == 0) fin = in;
    if (con == -1 && s > 0)
      s--;
    else if (con == 1)
      s++;
    sweep[in] += s;
    in++;
    in %= c.size();
  }
  in = -1;
  for (int i = 0; i < c.size(); i++) {
    if (sweep[i] == 0) {
      in = i;
      in++;
      in %= c.size();
      break;
    }
  }
  if (in == -1 && c.size() != 0) {
    cout << "1.00";
    return 0;
  }
  fin = -1;
  double sum = 0.0, an = -1;
  while (c.size() != 0 && in != fin) {
    if (fin == -1) fin = in;
    if (sweep[in] == 1 && an == -1) an = get<0>(c[in]);
    if (sweep[in] == 0) {
      if (get<0>(c[in]) < an)
        sum += get<0>(c[in]) - an + 2 * Pi;
      else
        sum += get<0>(c[in]) - an;
      an = -1;
    }
    in++;
    in %= c.size();
  }
  cout << setprecision(20) << (sum / (2 * Pi)) << "\n";
  return 0;
}
