AIR MATH

Math Question

Malia tried to prove that \( \cos (\theta)=\sin \left(90^{\circ}-\theta\right) \) using the following diagram. Her proof is not correct.
Statement Reason
\( 1 \quad m \angle C=90^{\circ}-\theta \quad \) The acute angles in a right triangle are complementary.
\( 2 \sin \left(90^{\circ}-\theta\right)=\frac{A C}{B C} \quad \) Definition of sine.
\( 3 \cos (\theta)=\frac{A C}{B C} \quad \) Definition of cosine.
\( 4 \cos (\theta)=\sin \left(90^{\circ}-\theta\right) \quad \) Substitution
What is the first mistake in Malia's proof?

Solution

solution

AIR MATH homework app,
absolutely FOR FREE!

  • AI solution in just 3 seconds!
  • Free live tutor Q&As, 24/7
  • Word problems are also welcome!
appstoreplaystore

Scan the QR code below
to download AIR MATH!

qrcode