Question
Average age of a class of 25 students is 13 years.
Average age of the class is increased by 30 months if the age of the teacher is included. Find the age of the teacher.Solution
Sum of the ages of all the students in the class = 25 × 13 = 325 years Sum of the ages of the students along with teacher = 26 × 15.5 = 403 years So the age of the teacher = 403 – 325 = 78 years
The minimum value of 45 sin2 θ + 28 cos2 θ is

Evaluate the following:
sin 60° × cos 30° + sin 30° × cos 60°
If 4sin² θ = 3(1+ cos θ), 0° < θ < 90°, then what is the value of (2tan θ + 4sinθ - secθ)?
- If 2cos²A + 3sin²A = 13/5, then find the value of (sec²A - 1)
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sin2 17˚ + sin2 19˚ + sin2 21˚ + sin2 23˚ + ……… + sin2 77˚ = ?
If tan² 45°- cos² 60° x sin 45° cos 45° cot 30°, then find the value of 'x'.
If SecA + TanA = 2√2 + 9, then find the value of Sin A + Cos A.