Search SchoolNGR

Saturday, 11 April 2026
Register . Login

Given that sin (5x - 28)o = cos (3x - 50)o,0 lt; x lt; 90o, find the value of x

Given that sin (5x - 28)o = cos (3x - 50)o,0 < x < 90o, find the value of x
Take Free Practice Test On 2026 JAMB UTME, Post UTME, WAEC SSCE, GCE, NECO SSCE
  • A 14o
  • B 21o
  • C 32o
  • D 39o
Correct Answer: Option B
Explanation:
Sin (5x – 28)o = cos (3x - 50)o
Since by the trigonometry relation
Sin(5x – 28)o = cos[90 – (5x – 28)]o
Hence cos(3x – 50)o = cos[90 – (5x – 28)]o
3x – 50 = 90 - (5x-28)
3x – 50 = 90 – 5x + 28
3x + 5x = 90 + 28 + 50
8x = 168
\(x = \frac{168}{8}=21^{\circ}\)

Share question on: