railway DFCCIL Executive 2025 Mock Test Quantitative Aptitude Trigonometry Trigonometric Ratios and Identities
Let x = r cos (t), y = r sin (t) cos (u), z = r sin (t)sin (u). Then the value of x2 + y2 + z2 is ___.
1
\(r^2 \cos(u)\)
2
r2
3
2r
4
r2 sin (t)