Find the value of \( 45^{\circ}-\sin ^{2} 30^{\circ} \) (a) \( \sin 45^{\circ} \cdot \cos 40^{\circ} \)
Upstudy AI Solution
Answer
Solution

Sign in to Unlock Answers for Free!
A Learning Platform Trusted by Millions of Real Students and Teachers.

Answered by UpStudy AI and reviewed by a Professional Tutor
Extra Insights
To find the value of \( 45^{\circ} - \sin^{2} 30^{\circ} \), we first need to calculate \( \sin^{2} 30^{\circ} \). We know that \( \sin 30^{\circ} = \frac{1}{2} \), so: \[ \sin^{2} 30^{\circ} = \left(\frac{1}{2}\right)^{2} = \frac{1}{4}. \] Now, substituting this value back into the expression: \[ 45^{\circ} - \sin^{2} 30^{\circ} = 45^{\circ} - \frac{1}{4}. \] Since \( 45^{\circ} \) can be expressed in decimal form as \( 45.0 \) degrees, we rewrite the expression as: \[ 45.0 - 0.25 = 44.75. \] Now let's look at the option given: \( \sin 45^{\circ} \cdot \cos 40^{\circ} \). Calculating \( \sin 45^{\circ} \): \[ \sin 45^{\circ} = \frac{\sqrt{2}}{2}. \] Now, we need to evaluate \( \cos 40^{\circ} \). This value is typically not a simple fraction, so we will leave it in symbolic form: \[ \sin 45^{\circ} \cdot \cos 40^{\circ} = \frac{\sqrt{2}}{2} \cdot \cos 40^{\circ}. \] To find the relationship, simplify the problem numerically and see if they match up. Both involve operations and approximations but seem to diverge from each other as \( \cos 40^{\circ} \) is not simply resolvable without an exact angle or calculator, while \( 44.75 \) is clearly defined. Thus, we conclude \( 45^{\circ} - \sin^{2} 30^{\circ} \) equals \( 44.75 \), providing a clear distinction from \( \sin 45^{\circ} \cdot \cos 40^{\circ} \).