#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
const long long INF = 2e18;
const int N = 1231234;
const long double pi = acos(-1.0);
const double eps = 1e-10;
int v, t;
int x, y;
long long r[N];
int n;
long long dis2[N];
pair<long double, long double> pd[N];
int dcmp(long double x) {
  if (fabs(x) < eps) return 0;
  return x > eps ? 1 : -1;
}
int main() {
  while (scanf("%d%d%d%d", &x, &y, &v, &t) != EOF) {
    r[0] = 1LL * v * t;
    int i, j;
    scanf("%d", &n);
    int f = 0;
    int tot = 0;
    for (i = 1; i <= n; ++i) {
      int a, b;
      scanf("%d%d%I64d", &a, &b, &r[i]);
      a -= x;
      b -= y;
      dis2[i] = 1LL * a * a + 1LL * b * b;
      if (dcmp(r[i] * r[i] - dis2[i]) >= 0) {
        f = 1;
      }
      if (dcmp(sqrt(dis2[i]) - r[0] - r[i]) >= 0) continue;
      long double delt;
      if (dcmp(r[0] - r[i] - sqrt(dis2[i])) >= 0) {
        delt = asin(r[i] / sqrt(dis2[i]));
      }
      if (dcmp(sqrt(dis2[i] - r[i] * r[i]) - r[0]) <= 0)
        delt = asin(r[i] / sqrt(dis2[i]));
      else
        delt = fabs(acos((dis2[i] + r[0] * r[0] - r[i] * r[i]) /
                         (2 * sqrt(dis2[i] * 1.0) * r[0])));
      long double cur = atan2(b, a);
      if (dcmp(cur - delt) < 0) {
        if (dcmp(cur + delt) < 0) {
          pd[tot++] = pair<long double, long double>(cur - delt + 2 * pi,
                                                     cur + delt + 2 * pi);
        } else {
          pd[tot++] =
              pair<long double, long double>(cur - delt + 2 * pi, 2 * pi);
          pd[tot++] = pair<long double, long double>(0, cur + delt);
        }
      } else {
        pd[tot++] = pair<long double, long double>(cur - delt, cur + delt);
      }
    }
    if (f) {
      puts("1.00000000000");
      continue;
    }
    sort(pd, pd + tot);
    long double cur = 0;
    long double pre = 0;
    long double sum = 0;
    pd[tot++] = pair<long double, long double>(3 * pi, 3 * pi);
    for (i = 0; i < tot; ++i) {
      if (dcmp(pd[i].first - cur) > 0) {
        sum += cur - pre;
        pre = pd[i].first;
        cur = pd[i].second;
      } else {
        cur = max(cur, pd[i].second);
      }
    }
    printf("%.10f\n", (double)(sum / (2 * pi)));
  }
}
