Trigonometric Identities Level 1 Practice Quiz: Basic Identities and Values
This Level 1 set builds the core skill of applying the three Pythagorean identities, complementary-angle relations and standard angle values to simplify trigonometric expressions. It is a beginner practice set on trigonometric identities for competitive exam aspirants, prepared by Aptitude360. Every question comes with a detailed written solution.
Topics covered in this trigonometric identities set
- Finding the other ratios of an acute angle when one ratio is given
- Expressions built on the sine-cosine, secant-tangent and cosecant-cotangent identities
- Complementary angles, such as sine of one angle divided by cosine of its complement
- Standard values of sine, cosine and tangent at common angles
- Problems where secant plus tangent or cosecant minus cotangent is given
- Finding sine times cosine when their sum is known
- Maximum and minimum of a sine plus cosine combination
- Products of tangents or cotangents of complementary angle pairs
Key trigonometric formulas for Level 1
- Pythagorean identity: \( \sin^{2}\theta+\cos^{2}\theta=1 \)
- Secant form: \( \sec^{2}\theta-\tan^{2}\theta=1 \)
- Cosecant form: \( \operatorname{cosec}^{2}\theta-\cot^{2}\theta=1 \)
- Complementary angle: \( \sin(90^{\circ}-\theta)=\cos\theta \)
- Paired sum and difference: \( (\sec\theta+\tan\theta)(\sec\theta-\tan\theta)=1 \)
- Range: \( |a\sin\theta+b\cos\theta|\le\sqrt{a^{2}+b^{2}} \)
Revision tips for basic trigonometric identities
- Memorise Pythagorean triplets so a missing side of a right triangle appears instantly
- When two angles add up to a right angle, convert one ratio into its co-ratio before simplifying
- If secant plus tangent is given, use the reciprocal of that value as secant minus tangent
- Square the sum of sine and cosine to reach their product directly
Who should take this Level 1 set
Beginners in Quant geometry and trigonometry preparing for SSC, banking, CAT or IPMAT should start here before moving to harder levels.